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Materials Science and Engineering A286(2000)1–10High-strength aluminum alloys containing nanoquasicrystallineparticlesAkihisa Inoue *,Hisamichi KimuraInstitute for Materials Research ,Tohoku Uni 6ersity ,Sendai 980-8577,JapanAbstractBy the use of homogeneous dispersion of nanoscale quasicrystalline particles in fcc-Al phase,new Al-based alloys with useful mechanical properties were developed.The structure consists of nanoscale icosahedral particles with a size of 30–50nm surrounded by fcc-Al with a thickness of about 5–10nm and no high-angle grain boundary is observed in the Al phase.The icosahedral phase has a high volume fraction of 60–70%.The unique structure is formed by the unique solidiﬁcation mode in which the icosahedral phase precipitates as a primary phase followed by solidiﬁcation of Al phase from the remaining liquid.The features of mechanical properties for the nanoquasicrystalline alloys are classiﬁed into three types,i.e.high tensile strength type of 800MPa in Al–Cr–Ce–Co and Al–Mn–Ce–Co systems high elongation type of 30%in Al–Mn–Cu–Co system and high elevated temperature strength type of 500MPa at 473K and 350MPa at 573K in Al–Fe–Cr–Ti system.These mechanical properties are superior to those for the conventional Al-based crystalline alloys and the extension of the new Al-based alloys to practical application has also been described.Published by Elsevier Science S.A.Keywords :Dispersion;Quasicrystalline particles;Icosahedral particles /locate /msea1.Importance of Al-based alloys with non-periodic structureMore recently,aluminum-based alloys with high strength and light weight have attracted rapidly increas-ing interest because of the increase in the importance of energy and environmental problems on the earth.It is well known that ordinary Al-based alloys have been developed by the use of the following conventional strengthening mechanisms;i.e.solid solution,precipita-tion,grain size reﬁnement,dispersion,work hardening and ﬁber reinforcement [1].However,the use of these conventional strengthening mechanisms leads to an up-per limit of tensile fracture strength of about 600MPa.If we want to fabricate a new Al-based alloy with much higher tensile strength,we must utilize a completely new strengthening mechanism.For the last decade,we have paid attention to a nonperiodic structure such as amorphous and icosahedral phases,on the basis of experimental evidences that the tensile strength of Al-based alloys increases to 1260MPa [2]by the formation of an amorphous single phase and to 1560MPa [3]bythe homogeneous precipitation of nanoscale fcc-Al par-ticles into an amorphous phase,as shown in Fig.1.Structure and mechanical properties of aluminum base alloys developed by the authors et al.are summarized in Fig. 2.It is again noticed that high mechanical strength exceeding 1000MPa is achieved by the forma-tion of an amorphous phase [4].However,these high strength values were obtained for the melt-spun ribbon alloys.For practical applications as high-strength Al-based alloys,it is essential to develop an Al-based alloy with high strength in a bulk form.We have already succeeded in developing bulk nanocrystalline alloys with a mixed structure of intermetallic compounds em-bedded fcc-Al matrix by the crystallization of Al-based amorphous phase [5].The bulk nanocrystalline alloys exhibit high mechanical strength of 700–1000MPa and have been commercialized as a commercial name of GIGAS [6].Subsequently,we have also developed bulk nanoquasicrystalline alloys in Al-based system exhibit-ing a good combination of high tensile strength,large elongation,high fatigue strength and high elevated-tem-perature strength [7–9].This paper is intended to re-view our recent results on the formation,microstructure and mechanical properties of bulk Al-based alloys con-*Corresponding author.0921-5093/00/$-see front matter Published by Elsevier Science S.A.PII:S 0921-5093(00)00656-0A.Inoue,H.M.Kimura/Materials Science and Engineering A286(2000)1–102taining nanoquasicrystalline particles as a main con-stituent phase.efulness of quasicrystalline phase as strengtheningmediumIt is important to clarify the usefulness of a qua-sicrystalline phase with a nonperiodic atomic conﬁgura-tion as a strengthening medium in Al-based alloys.Ithas been reported that the quasicrystalline phase cancontain dislocations,but their movement is verydifﬁcult at room and elevated temperatures because themovement causes the destroy of the quasiperiodic lat-tice[10].With the aim of obtaining experimental resultson the mechanical properties of the icosahedral phaseitself,we prepared a large single quasicrystalline ingotof Al70Pd20Mn10alloy with a diameter of about10mmand a length of120mm by the Chochralski method[11].By using the large single quasicrystalline ingot,ithas been clariﬁed that the Young’s modulus(E)is200GPa and the high E value remains almost unchanged inthe temperature range up to about800K[12].The yieldstrength also does not exhibit a signiﬁcant decrease inFig.2.Microstructure and mechanical strength of aluminum basealloys developed by our group for the last decade.Fig.1.Change in the tensile strength of Al-based alloys with calendar year.the temperature range up to800K and the coefﬁcient of the expansion shows low values of1.1–1.4×10−5 K−1[12].However,the fracture toughness shows a very low values below3MPa m in the range up to 600K[13].Owing to the low fracture toughness,the stoichiometric icosahedral alloy itself cannot be used as a strengthening material.However,their strength char-acteristics are good enough to be used as a strengthen-ing medium in an fcc-Al phase with high ductility. 3.Microstructure and mechanical properties ofAl-based alloys containing nanoquasicrystalline particles We examined the possibility of forming a nanoscale mixed structure consisting of nanoscale particles sur-rounded by fcc-Al phase in Al-based alloys.It has previously been reported that an icosahedral quasicrys-talline single phase is formed in rapidly solidiﬁed Al80Mn20[14,15],Al84Cr16[16]and Al86V14[17,18]bi-nary alloys.These icosahedral single phase alloys are in an extremely brittle state.Consequently,we examined the compositional dependence of microstructure and mechanical properties of the Al–Mn–Ce alloys[19], because of the expectation that the addition of CeA.Inoue,H.M.Kimura/Materials Science and Engineering A286(2000)1–103 increases the quenching effect[20]and enables theformation of aﬁnely mixed structure of icosahedral andfcc-Al phases.Fig.3shows the compositional depen-dence of structure,bending ductility and tensile fracturestrength of the melt-spun Al–Mn–Ce ternary alloys[19].A mixed structure of icosahedral and fcc-Al phasesis formed in a high Al concentration more than90at.%Al and the mixed phase alloys exhibit good bend-ing ductility and high tensile strength exceeding1000MPa.It is noticed that the tensile strength reaches ashigh as1320MPa.Fig.4shows a TEM image andselected-area electron diffraction pattern of the melt-spun Al92Mn6Ce2alloy with high strength of1320MPa[19].The alloy consists of spherical icosahedral particleswith a size of about50nm surrounded by an fcc-Allayer with a thickess of5–10nm.The reﬂection ringsresult from the icosahedral particles,indicating that theicosahedral particles have random orientations.Theseresults reveal that the nanoscale icosahedral particlesappear as a primary precipitation phase,followed byFig.5.Bright-and dark-ﬁeld TEM images(a and b)and selected-area electron diffraction pattern(c)of a rapidly solidiﬁedAl94.5Cr3Ce1Co1.5alloy.The dark-ﬁeld image was taken from a partof reﬂection rings of the icosahedral phase.positional dependence of structure,bending ductility and tensile fracture strength(|f)of rapidly solidiﬁed Al–Mn–Ce alloys.the solidiﬁcation of fcc-Al phase from the remaining liquid.A similiarﬁnely mixed structure has also been obtained in a melt-spun Al94.5Cr3Ce1Co1.5alloy with high tensile strength of1340MPa,as shown in Fig.5 [20].The icosahedral particles are as small as about40 nm and are surrounded by an fcc-Al phase without high-angle grain boundary.The primary precipitation of the icosahedral phase is presumably due to the existence of icosahedral clusters in the supercooled liquid of the Al-based alloys.The absence of the high-angle grain boundary has been attributed to an annihi-lation of grain boundary at the icosahedral/fcc–Al interface.The high tensile fracture strength exceeding 1000MPa has been obtained in melt-spun Al93.5Cr3Ce l Co l.5M1(M=Ti,Mn,Fe,Co,Ni,Cu,Zr or Mo)alloys[21]as well as in melt-spun Al94Mn4M2 and Al93Mn5M2(M=Fe,Co,Ni,Cu)alloys[22]. Here,it is important to point out that the good mechanical properties are obtained only in the solidiﬁ-cation mode in which nanocrystalline particles precipi-tate as a primary phase,followed by the solidiﬁcation of fcc-Al phase from the remaining liquid.Even when the two phases of icosahedral and fcc-Al are formed, Al-based alloys with high strength and ductility have been obtained in the following two kinds of solidiﬁca-tion processes,i.e.(1)the formation of fcc solid solu-tion,followed by the precipitation of icosahedral phase from the solid solution,and(2)the primary precipita-tion of fcc-Al phase,followed by the solidiﬁcation of icosahedral phase from the remaining liquid.Fig.4.Bright-ﬁeld TEM image and selected-area electron diffraction pattern of a rapidly solidiﬁed Al92Mn6Ce2alloy.A .Inoue ,H .M .Kimura /Materials Science and Engineering A 286(2000)1–104Fig. 6.Changes in the tensile fracture strength (|f )and Vickers hardness (H v )as a function of reduction in ratio for the cold-rolled Al 92Mn 6Ce 2and Al 94.5Cr 3Ce 1Co 1.5alloys.4.Cold workability of Al-based alloys containing nanoscale icosahedral particlesIt was found that the Al-based icosahedral alloys have good cold workability which is shown by easy cold rolling to over 70%reduction in thickness [23].A number of deformation markings are observed on the surface of the cold-rolled ribbons,but no appreciable crack is observed even after cold rolling.Fig.6shows the change in the Vickers hardness (H v )as a function of reduction ratio for the melt-spun Al 92Mn 6Ce 2and Al 94.5Cr 3Ce 1Co 1.5alloys with the nanoscale mixed struc-ture.The H v values are about 350in as-spun state and decrease signiﬁcantly to about 200with increasing re-duction ratio to 70%,indicating that a distinct work softening occurs for the nanoscale mixed phase alloys.Fig.7shows TEM images and selected-area electron diffraction pattern of the Al–Mn–Ce and Al–Cr–Ce–Co alloys subjected to cold-rolling to 70and 50%reductions in thickness.In comparison with the TEM images shown in Figs.4and 5,one can notice that the particle size of the icosahedral phase decreases from about 50nm in as-spun state to about 5–10nm in the cold-rolled state.The signiﬁcant decrease in the particle size of the icosahedral phase itself is presumably due to the fragmentation of the icosahedral phase,accompa-nying the spontaneous ﬁlling up of the ductile fcc-Al phase to fragmented region.Based on the TEM images,the distinct work softening phenomenon is interpreted to result from an increase in the icosahedral /fcc-Al interface region by the reﬁnement of the icosahedral particles followed by the sinking of dislocations at the interface.The sinking of dislocations is supported from the absence of dislocations in the cold-rolled icosahe-dral and Al phases.5.Microstructure and mechanical properties of bulk icosahedral base Al alloys produced by warm extrusion of atomized powders5.1.High strength -and high ductility alloysA ﬁnely mixed structure consisting of nanoscale icosahedral particles surrounded by fcc-Al phase with-out grain boundary was formed by the gas atomization process.The atomized powders were extruded at 673K well below the decomposition temperature of about 750K.Fig.8shows the relation between tensile fracture strength (|f )and fracture elongation (m f )for the ex-truded bulk base alloys in the Al–Cr–Ce–Co and Al–Mn–Co systems,together with the data of conven-tional Al-based crystalline alloys [24].The icosahedral base alloys exhibit higher mechanical strength of 500–800MPa and larger elongation of 5–25%,as compared with the conventional Al-based alloys.The mechanicalFig.7.Bright-ﬁeld TEM images and selected-area electron diffraction patterns of the as-quenched and cold-rolled to 50%reduction in thickness for the Al 94.5Cr 3Ce 1Co 1.5alloy.A .Inoue ,H .M .Kimura /Materials Science and Engineering A 286(2000)1–105Fig.8.Relation between tensile strength (|f )and elongation (m f )for bulk icosahedral base alloys in Al–Cr–Ce–Co,Al–Mn–Ce–Co and Al–Mn–Co–Cu systems produced by warm extrusion of atomized powders.The data of the conventional fcc–Al alloys are also shown for comparison.increases to 16J cm −2which is higher than that (11J cm −2)for the 7075-T6alloy as shown in Fig.9[25].In addition,Fig.10shows that the icosahedral base Al 94Cr 2.5Co 1.5Mm 1Zr 1alloy exhibits high fatigue en-durance limit of 240MPa at room temperature and 210MPa at 423K [26].Considering that the fatigue en-durance limit of the 7075-T6alloy is about 120MPa at room tempature [27],it is concluded that the icosahe-dral base alloy has signiﬁcantly improved fatigue strength,at room and elevated temperatures.The Al 94Cr 2.5Co 1.5Ce 1Zr 1alloy also has a high Young’s modulus of about 100GPa as well as a rather high elevated-temperature strength of about 200MPa at 573K [24].5.2.High ele 6ated -temperature strength -type alloysRecently,there has been strong demand to develop a new Al-based alloy with much improved elevated-tem-perature strength because the development is expected to cause a saving of energy and a maintenance of good atmosphere on the earth.We examined the possibility of forming an icosahedral single phase in Al–Fe–Cr–Ti system,because the Fe,Cr and Ti elements have very low atomic mobility in Al phase [28].There have been no data on the formation of an icosahedral phase in Al–Fe base system.It was found that a mostly single icosahedral phase is formed in a melt-spun Al 84.2Fe 7.0Cr 6.3Ti 2.5alloy,as shown in Fig.11[29].The alloy consists of an icosahedral phase with a grain size of about 120nm and no distinct second phase is seen in the bright-ﬁeld TEM image.The selected-area electron diffraction patterns also reveal the ﬁve,three-and two-fold symmetries.Based on the formation of the mostly single icosahedral phase in the Al–Fe–Cr–Ti alloy,the atomized powders were produced by choos-ing a further Al-rich composition of Al 93Fe 3Ti 2Cr 2.As shown in Fig.12,the atomized powder of the Al-rich alloy consists mainly of icosahedral and fcc-Al phasesFig.9.Relation between tensile strength and impact fracture energy for the bulk icosahedral Al 93–95(Cr,Mn,Ni,Cu)5–7alloys produced by the powder metallurgy technique.Fig.10.Relation between stress amplitude and cycles to failure at room temperature and 423K for the bulk icosahedral Al 94Cr 2.5Co 1.5Mm 1Zr 1alloy produced by the powder metallurgy technique.properties can be divided into two kinds;i.e.high strength alloys in Al–Cr–Ce–Co system containing rare earth element and high ductility-type alloys in Al–Mn–Co system without rare earth element.When the alloy components of the high ductility-type alloys are further adjusted,the elongation increases further to about 30%.The Charpy impact fracture energy alsoA .Inoue ,H .M .Kimura /Materials Science and Engineering A 286(2000)1–106Fig.11.Bright-ﬁeld TEM image (a)and selected-area electron diffrac-tion patterns (b–d)for a rapidly solidiﬁed A 84.2Fe 7.0Cr 6.3Ti 2.5alloy.force goal level of USA,as shown in Fig.14.It is noticed that the tensile fracture strength of the Al–Cr–Ti alloys is in the range of 450–500MPa at 473K and 320–350MPa at 573K which exceed the air-force goal level in the wide temperature range up to 573K.The high elevated temperature strength is also supported from the result that the Vickers hardness remainsFig.12.X-ray diffraction patterns of an Al 93Fe 3Ti 2Cr 2alloy in as-atomized and extruded bulk states.Fig.13.Temperature dependence of 0.2%proof stress (|0.2)as a function of testing temperature for the extruded bulk Al 91–93Fe 3–5-Cr 2Ti 2alloys produced by the powder metallurgy technique.and the mixed structure remains unchanged in the extruded bulk alloys [29].The icosahedral phase in the extruded bulk alloy is also conﬁrmed in the bright-ﬁeld TEM image and selected-area electron diffraction pat-terns.Besides,it has been clariﬁed that the phase has high thermal stability and begins to decompose at 790K in the continuous heating at 0.67K s −1[29].The tensile yield strength,tensile fracture strength and elon-gation of the extruded bulk Al 93Fe 3Ti 2Cr 2alloy are 550MPa,650MPa and 4%,respectively,at room tempera-ture and 330MPa,360MPa and 2%,respectively,at 573K [29].Fig.13shows the temperature dependence of the 0.2%proof stress for the extruded bulk icosahe-dral Al–Fe–Cr–Ti alloys after heating for 100h at each testing temperature,together with the data [30]of the conventional Al-based alloys.The proof stress shows much higher values over the whole temperature range up to 700K as compared with those for any kinds of conventional Al alloys with high-elevated tem-perature strength.We further compared the present elevated temperature strength with that [31]for air-A .Inoue ,H .M .Kimura /Materials Science and Engineering A 286(2000)1–107Fig.14.Temperature dependence of ultimate tensile strength (|UTS )for the extruded bulk Al 91–93Fe 3–5Cr 2Ti 2alloys produced by the powder metallurgy technique.parison of mechanical properties of Al-based alloys with those of the conventional 7075-T6alloy.alloys exhibit higher tensile strength,higher elevated temperature strength,higher Charpy impact fracture energy,better cold workability,larger elongation and higher Young’s modulus,as shown in Fig.15.6.Change in the melt-spun structure with periodic group of solute elementsIt was shown that the nonequilibrium icosahedral and Al mixed phases are formed in the melt-spun Al–Fe-,Al–Mn-and Al–Cr-based alloys.We further examined the melt-spun structure of the Al-based alloys containing solute elements with different periodic groups in the periodic table.The melt-spun structure consists of nanogranular amorphous and fcc-Al phases for Al 94V 4Fe 2and Al 93Ti 5Fe 2alloys,as shown in Fig.16.These nanogranular alloys also had high tensile fracture strengths of 1390and 1210MPa,respectively.Furthermore,it has previously been reported that an amorphous single phase is formed in the melt-spun Al 93Ln 7and Al 93Ln 6Ni 1alloys [32].The structural data are summarized in Table 2.It is clearly seen that the structures of the melt-spun Al-rich alloys containing 5–7at.%solute elements change systematically in the order of Al +compound Al +quasicrystalline Al +quasicrystalline (or amorphous) Al +amor-phous phase with decreasing periodic number of solutealmost unchanged even after the long-time annealing for 1000h at 573K.Furthermore,the high elevated temperature strength has enabled the maintenance of good wear resistance even at a high sliding velocity of 2m s −1.Table 1summarizes the features of quasacrystalline base aluminum alloys in a bulk form produced by the powder metallurgy technique.The mechanical proper-ties of the quasicrystalline base alloys can be divided into the following three groups;i.e.(1)high-strength type in Al base alloys containing rare earth elements as is evidenced from the high tensile strength of 800MPa;(2)high ductility type in Al base alloys without rare earth elements as is evidenced from the large elongation of 30%,and (3)high-elevated temperature strength in Al base alloys containing low diffusivity elements of Fe,Cr and Ti as is evidenced from high tensile strength of 500MPa at 473K and 350MPa at 573K.In compari-son with the mechanical properties of the 7075-T6alloy,the high-strength type nanoquasicrystalline baseTable 1Features of mechanical properties for quasicrystalline Al-based bulk alloys produced by the powder metallurgy technique Alloy system Structure TypeMechanical properties Al–Cr–Ce–M High-strength alloy Al +Q |f ²600 800MPa Al–Mn–Ce m p ²5 10%Al–Mn–Cu–M High-ductility alloyAl +Q|f ²500 600MPa m p ²12 30%Al–Cr–Cu–M |f ²350MPa at 573KHigh-elevated temperature strength alloyAl–Fe–Cr–TiAl +QAl +Q +Al 23Ti 9A .Inoue ,H .M .Kimura /Materials Science and Engineering A 286(2000)1–108Fig.16.Bright-ﬁeld TEM images and selected-area electron diffrac-tion patterns of rapidly solidiﬁed Al 94V 4Fe 2(a,b)and Al 93Ti 5Fe 2(c,d)alloys.Fig.17.Structures of rapidly solidiﬁed Al–Ln,Al-ETM and Al-LTM binary and Al-Ln-ETM,Al-Ln-LTM and Al-ETM-LTM ternary alloys.binary system.It is readily recognized that the forma-tion of the nonperiodic structure is common for the melt-spun Al-based alloys.Consequently,there is a strong possibility of developing a new-type Al-based alloy by the use of the nonperiodic structures.That is,the progress of the use of the nonperiodic structure is expected to open up new science and engineering ﬁelds in Al-based alloys.7.Strengthening mechanismsIt is ﬁnally important to discuss the strengthening mechanism for the Al-based alloys containing nanoscale nonperiodic phases in the as-spun ribbon and extruded bulk states of the Al–Cr–Ce–Co,Al–V–Fe and Al–Fe–Cr–Ti systems.Fig.18shows the Hall–Petch relation [33,34]between the 0.2%proof stress(|0.2)and d s−1/2for the Al-based alloys.Here,d s repre-sents the distance between the surface of the nonperi-odic particles.A good linear relation in the Hall–Petch relation is recognized in the d s over 40nm and the further decrease in d s leads to the deviation from the Hall–Petch relation.The ﬁne structure with d s below 40nm has a unique strengthening mechanism which is different from that for the Hall–Petch relation.That is,elements.This result indicates that the quenching effect leading to the formation of structure increases with decreasing periodic number of the solute elements.The systematic change has been interpreted by the concept that the glass-forming ability increases by the increases in the difference in atomic size ratios and negative heats of mixing among constituent elements.Fig.17summarizes the structures of the melt-spun Al–Ln,Al-ETM and Al-LTM binary and Al–Ln–ETM,Al–Ln–LTM and Al–ETM–LTM ternary al-loys.When appropriate alloy compositions described in the present review are selected,the nonperiodic struc-tures of amorphous and quasicrystalline phases are formed in almost all alloy systems except Al–LTMTable 2Structures of rapidly solidiﬁed Al 93-95Ln 3–4LTM 2–3and Al 93-95ETM 3–4LTM 2–3alloys ElementLanthanide ETM LTM Fe Co Ni Cu Cr Mn VTi LnAmAl +AmAl +Am /Al +QAl +QStructureAl +Comp.A.Inoue,H.M.Kimura/Materials Science and Engineering A286(2000)1–109Fig.18.Hall–Petch relation between|0.2and d s−1/2for quasicrystalline base Al alloys in the melt-spun ribbon and extruded bulk forms.The d s represents the space between the icosahedral particles.Fig.19.Martin relation between|0.2and ln(2r s/r0)/u s for quasicrystalline base Al alloys in the melt-spun ribbon and extruded bulk forms.The r s is the radius of the icosahedral particle,r0is the core radius of dislocation in Al phase and u s is the spacing between the icosahedral particles.A.Inoue,H.M.Kimura/Materials Science and Engineering A286(2000)1–10 10theﬁne structure has a high volume fraction of inter-face boundary which cannot act as effective resistant barrier against movement of dislocations.Theﬁne grain structure enables an easy sliding along the inter-face boundary as well as a sinking of dislocations at the interface,leading to the absence of dislocations in the fcc-Al matrix.In the discussion on various strengthen-ing mechanisms,we notice that the Martin relation[35] between|0.2and ln(2r s/r0)u s yields a good linear rela-tion over the whole particle size range,as shown in Fig.19.Here,r s,r0and u s represent the radius of the nonperiodic particle,core size of dislocation and dis-tance between surfaces of the nonperiodic particles, respectively.The origin of the Martin relation is similar to that for the Orowan relation[36].First,the disloca-tions are pilled up by the precipitation particles,but the subsequent dislocation can pass through by cutting the particles.When this concept is applied to the present nonperiodic alloy,the dislocationsﬁrst pile up against the nonperiodic structure followed by annihilation of dislocations at the interface.The annihilation of dislo-cations at the interface seems to have the similiar action as that for the passage of dislocations by the precipita-tion particle,because the dislocations in these situations cannot play a role in the further increase inﬂow stress.A further detailed universal strengthening mechanism which can be applied to the nanoscale mixed structure in a wide grain size range is under investigation and the further extension of grain size range in various alloy systems is expected to lead to a deﬁnite universal inter-pretation of the strengthening mechanism in the nanoscale,microscale and macroscale structure ranges.8.ConclusionsWe developed a new type of high-strength Al-based alloys containing nanoscale nonperiodic phases by the controls of structure,composition and stability of the supercooled liquid.The development of new materials by controlling the supercooled liquid state in Al-based alloys had not been tried up to date.The present success of the conventional method is encouraging for the development of the other type of new materials with high functional properties which cannot be obtained by the conventional processing methods.References[1]H.Jones,Aluminum Alloys54(1978)274.[2]A.Inoue,N.Matsumoto,T.Masumoto,Mater.Trans.JIM31(1990)493.[3]Y.H.Kim, A.Inoue,T.Masumoto,Mater.Trans.JIM31(1990)747.[4]A.Inoue,K.Ohtera,A.P.Tsai,T.Masumoto,Jpn.Appl.Phys.27(1988)L479.[5]K.Ohtera,A.Inoue,T.Terabayashi,H.Nagahama,T.Ma-sumoto,Mater.Trans.JIM33(1992)775.[6]YKK Catalog(1995).[7]A.Inoue,H.M.Kimura,Mater.Sci.Forum235–238(1997)873.[8]A.Inoue,Handbook on the Physics and Chemistry of RareEarths24(1997)83.[9]A.Inoue,Prog.Mater.Sci.43(1998)365.[10]S.Takeuchi,Tetsu-to-Hagane78(1992)1517.[11]Y.Yokayama,A.P.Tsai,A.Inoue,T.Masumoto,Mater.Trans.JIM32(1991)1089.[12]Y.Yokoyama,A.Inoue,T.Masumoto,Mater.Trans.JIM34(1991)135.[13]Y.Yokayama,A.Inoue,T.Masumoto,Mater.Trans.JIM34(1993)135.[14]T.Masumoto,A.Inoue,M.Oguchi,K.Fukamichi,K.Hiraga,M.Hirabayashi,Trans.Japan 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第三章准晶结构与材料性能

第三章
准晶材料
准晶体发现：20世纪80年代晶体学研究中的一次突破。 84年底，D.Shechtman等人，在急冷凝固Al Mn合金中发现具有五重旋转对称但并无无平移周期性的合金相。准晶体（Quasicrystal）—无平移同期性但有位置序的晶体。郭可信等在对高温合金中的四面体密堆合金相的高分辨电子显微镜观察到： 84年夏发现五重旋转对称的电子衍射图， 85年初在Ti2Ni合金中发现了二十面体准晶。 85年以来先后发现了八次、十次对称准晶以及一维和立方准晶。
从彭罗斯图可以看到，如果绕5次轴转动2π/5 ，图案又回复到原来的形状，这就是准晶体具有5次旋转对称性的表现，同时这种图案具有准周期性的长程序。
晶体与准晶的对称轴与基转角关系
2、二维准晶
• •
87年首先在急冷的Cr5Ni3Si2 和V15N10Si合金中观察到 8 次准晶，随后又在 Mn4Si ， Mn82S15A13〕等合金中观察到8次准晶。 • 8次准晶准周期面上由两个结构基元组成：正方形，45°菱形。两种结构基元的准周期排列，构成8次准点阵，这些正方形、菱形的边都落在成45°的8个方向上，阵点排列成费波纳斯链，相邻阵点间的距离之比的数列由1，组成。与45°角有关。
准晶：20世纪80年代晶体学研究中的一次突破
准晶聚合物（quasicrystalline polymer）结构使得新一代基于光的通信技术成为可能目前，在光子电路中，光不能进行锐角的转折，准晶点阵技术可使光在电路中传播时产生锐角转折，这将推动高速通信和计算设备的发展。普林斯顿大学的研究人员已经发现了制造准晶聚合物结构的方法，代表了光子学潜在的重大进步。此结构能够控制光的传播，使得光子通信系统成为可能。

准晶体_精品文档

准晶体摘要：准晶体是一种具有有序但不具备传统晶体完全周期性重复结构的材料。

本文将介绍准晶体的基本概念、发现历史、晶体学特征、结构特点以及其在材料科学领域的应用等方面。

通过对准晶体的深入研究，我们可以更好地了解这种材料的特殊性质，从而为今后的材料设计与合成提供更多可能性。

1. 引言准晶体是一种介于晶体和非晶体之间的特殊材料，其结构既具有一定的有序性，又存在非晶体所特有的无规则局部结构。

准晶体的发现给传统晶体学观念带来了很大的冲击，使得人们重新审视晶体结构的多样性和复杂性。

2. 发现历史准晶体的发现可以追溯到20世纪70年代初。

当时，关于准晶体存在的猜测和研究已经逐渐增多，但直到1975年才有科学家首次成功合成出了一种具有五重旋转对称性的准晶体。

这个发现引起了极大的轰动，并引发了整个科学界对准晶体的深入研究。

3. 晶体学特征准晶体的晶体学特征与传统晶体存在一定的差别。

准晶体的晶胞通常具有五重旋转对称性，而不是晶胞中心对称或其他常见的对称性。

此外，准晶体的点阵常数通常不是整数，这也是准晶体与普通晶体的一个显著区别。

4. 结构特点准晶体的结构特点是其与传统晶体最大的不同之处。

准晶体的结构在宏观上呈现出高度有序的态势，但在微观上却存在着一些局部无规则的结构。

这种具有非晶体特点的局部结构是准晶体与普通晶体的本质区别。

5. 应用与前景准晶体具有独特的结构和性质，将为材料科学领域带来许多新的应用与前景。

准晶体在催化剂、材料增强、信息存储、光学器件等方面都有着广泛的应用。

未来，通过对准晶体的深入研究，我们可以更好地利用准晶体的特性，实现更高效、更可靠的新型材料的开发与制备。

6. 结论准晶体作为一种介于晶体与非晶体之间的特殊材料，其结构和性质的研究具有重要的科学意义和应用价值。

通过对准晶体的深入研究，我们可以更深入地了解准晶体的结构特点，为今后的材料设计与合成提供更多的可能性。

相信在不久的将来，准晶体将在材料科学领域发挥着重要的作用。

准晶材料的制备(color)

准晶材料的制备整理：滕飞 2011-11-021以色列科学家丹尼尔-舍特曼（Daniel Shechtman）因发现准晶体而获得2011年诺贝尔化学奖。

2准晶的概念准晶材料是介于周期结构与无序结构之间的一类新发现的凝聚态，具有传统的晶体材料所不具备的对称性，由于其结构的特殊性，例如它具有五次和十次等特殊的对称性。

因此它具有许多优良的机械性能、物理化学性能和光电磁性能。

准晶分类 ¾从热力学角度热力学亚稳态准晶：在某个温度区间退火会变为晶体类似相稳态准晶：热力学上是稳定的¾按结构可分为一维准晶二维准晶：八次、十次和十二次准晶三维准晶：主要是二十面体3¾一维准晶：是由二维十面体准晶中的一个二次准周期轴（与十次轴正交）变为二次周期轴而生成的，即一维准晶具有两个正交的周期方向和一个与它们正交的准周期方向。

二维准晶：在一个平面上的两个方向上显示准周期性，而在其法线方向呈现周期性。

二维准周期平面的特征可以用这个具有周期性的旋转轴来表示，从而分为不同形态的二维准晶。

三维准晶：主要是二十面体，它指的是在空间中任何三个正交方向上都呈现准周期性，而无任何周期性方向。

¾¾4准晶体的类型现在已在100多种金属合金体系中发现了准晶相，如已有报导的准晶合金有基于Al、Cu、Mg、Ni、Ti、Zn、Zr等的合金。

5影响准晶生长的因素准晶形成过程大致可有4种基本情况：气体→准晶体、溶体(熔体)→准晶体、晶体→准晶体、非晶→准晶体。

影响准晶生长的因素合金成分，准晶只能在一定范围内形成；合金成分原子尺寸，主要元素的原子半径大小相近，以较小的原子为中心；原子尺寸电子结构，组元的电子结构与准晶的形成能力有内在联系；电子结构冷却速度，影响较大，冷却速度较大有利于准晶的形成，冷却速度过冷却速度高会导致过饱和固熔体先于准晶形成甚至出现非晶，因此冷去速度应控制在一个适应的范围；温度和压力，改变结构的束缚状态和结构熵， A1-Cu-Fe系合金，压力温度和压力增加有助于晶体等向准晶转变，增加压力可使冷却速度降低而保持效果不变。

准晶体的发展及其应用

2）磁性能：对高电阻的准晶的磁阻，当温度不高时，准晶体磁致电阻情况很复杂，但若温度大于100K时，磁阻将随外场的增加而减少。
3）热性能：准晶体的热性能一般不高，即它的导热系数K很小，且与温度密切有关。
4）准晶都很脆，将它作为结构材料使用尚无前景、准晶的特殊结构对其物理性能有明显的影响。
5）准晶的密度低于其晶态时的密度，这是由于其原子排列的规则性不及晶态严密，但其密度高于非晶态，说明其周期性排列仍是较密集的。
04Part four 准晶体的制备
如何制备准晶体
除了少数准晶为稳态相之外，大多数准晶相均属于亚稳态产物，它们主要通过快冷方法形成，此外经离子注入混合或气相沉积等途径也能形成准晶。准晶的形成过程包括形核和生长两个过程，故采用快冷方法时其冷却速度要适当控制。
制备方法：定向凝固法、自熔体法、深过冷快速凝固法。
钬-镁-锌十二面体准晶
Penrose拼图。可以看到平面中仅由宽窄两种菱形构成，中间的球也由这两种菱形构成
谢谢您聆听
三维物理空间的材料，其中的原子有二维是准周期分布的，另外一维是周期分布的。实验上发现，二维准晶有十次准晶、十二次准晶、八次准晶、和五次准晶四类。三、三维准晶
三维物理空间的材料，其中的原子在三维上都想准周期分布的。实验上已经发现的三维准晶有二十面体和立方准晶两大类。
准晶体的性质
3）理论上的准晶体应有下述一些性质：均一性、各向异性、对称性、自限性、最小内能性、稳定性
准晶体的发展及其应用
准晶体的定义
准晶体
亦称为“准晶”或“拟晶”，是一种介于晶体和非晶体之间的固体结构。在准晶的原子排列中，其结构是长程有序的，这一点和晶体相似；但是准晶不具备平移对称性，这一点又和晶体不同。普通晶体具有的是二次、三次、四次或六次旋转对称性，但是准晶的布拉格衍射图具有其他的对称性，例如五次对称性或者更高的六次以上对称性。

精品准晶简介演示文档

有助于提高使用寿命, 完全符合厨房炊具的标准。
有密度小、耐蚀和耐氧化的优点,
在航空和汽车工
、
与基底结合性好等优点。
准晶的导热性较差，但由于层厚较薄,
业的发动机等部件中,
有潜在应用价值。
不会影响到
不粘锅的使用。
(2)准晶作为构造材料增强相的应用
(b)准晶纳米颗粒增强Al基合金
(a)准晶相作为时效强化相
(4)固态反响法将叠压在一起的多层纯组元薄膜在
一定温度下加热进展互扩散, 也可以获得准晶。
(5)真空气相沉积法将两个纯组元加热到工作温度,
影响准晶形成的因素
(1)合金的成分对于能形成准晶的合金系统, 准晶只
能在一定的成分范围内形成。
(2)电子构造已经发现在Al-Mn 二元系中, 不易形成
Mn-Mn 近邻原子对, Al42Mn12二十而体有很高的稳
类合金(M-VIII组元素)
二十面体相:二元系
二十面体相:
二十面体相:Mg
二元系
NiTi
Al-Mn
Al-Pd
Al-Cr
4CuAl
6 Al-2.5Li-1.2Cu-0.9Mg-0.1Zr
2 FeTi
2
八边形相:三元系
三元系Cr-Ni-Si
Al-Mn-Si Al-Mn-Fe Pd59V20.5Si20.5
包括Melt-Spining法, 电子束外表扫描法和雾化制粉
法。
(2)退火法利用某些非晶态合金加热时的转变或某
些合金经固溶淬火处理后进展人工时效时的析出能
获得准晶相。如Al-Cu-Li准晶
(3)高能粒子束辐照法将多层纯组元薄膜叠压在一
起, 用高能电子束或离子束进展辐照可以获得准晶。

准晶材料制备技术

电子衍射图在晶体学中的应用》《高分辨电子显微学》
晶体的结构是高度有序化的,它具有以原胞周期性排列为特征的程平移序和满足晶体学点群为标志的最近邻价健长程指向序.
相反地,非晶固体却不具备这种晶体长程相关性. 准晶体作为一种被新发现的晶体结构形态,在结构特征上是处于两者之间的.
增加Al-Mn合金中的Mn含量，准晶的硬度随之增大。 A178 Mn22 准晶在室温的硬度超过700kg/mm2。
准晶虽然硬度高，耐磨性能并不一定好，Al-15wt%Mn2wt%Fe准晶的耐磨性比相应的晶态差。
准晶材料的特性
8、准晶的韧性差：大多呈穿晶断裂，故准晶难于单独作为结构材料
使用，但可以将韧性好的晶态材料作基体，以准晶作弥散第二相，可以提高材料的综合性能。如果将准晶的晶粒减小到纳米尺寸后，准晶的强度和韧性都有很大提高，如A1基合金中准晶晶粒减小到纳米量级后，材料中准晶含量达70 -80％，材料的强度和韧性都超过不含准晶的同类合金。
准晶材料的特性
6、磁性能——较为关注但知之甚少研究Al2 M n系准晶合金的直流和交流磁化率与温度之间的关系发现： ➢ 磁化率与温度之间遵守居里-外斯规律, 显示负的居里温度，
并在约10K时存在自旋玻璃转变。 ➢ 直流磁化率与温度关系求出含M n为20at%的Al2Mn及
Al2Mn2Si系平均有效磁矩为1. 4μB。 ➢ 进一步核磁共振、核比热与磁比热以及饱和磁矩研究发现，
准晶材料的特性
9、光学特性
高质量的准晶样品具有与绝缘体、半导体不同的光学特性。块体的纯准晶或准晶薄膜，在很宽的波长范围内均有60%的反射率，比导电材料Al、Fe要低，但优于半导体材料Si和绝缘材料。
6.2 准晶的形成机理

准晶简介-精品文档

04
准晶的未来展望
准晶的未来展望
• 准晶是一种特殊的固体物质，其结构表现出长程有序但缺乏平移对称性的特点。自从准晶被发现以来，其独特的物理性质和潜在的应用价值一直吸引着科学家的关注。为了进一步推动准晶领域的发展，我们有必要对准晶的未来展望进行探讨。
THANKS
感谢观看
• 准晶是一种特殊的固体物质，它们具有长程有序的结构，但缺乏平移对称性。这意味着准晶呈现出一种介于晶体和非晶体之间的特性。下面将详细介绍准晶的形成机制、发现历程以及在自然界和实验室的分布。
03
准晶的研究与应用
准晶的科学研究
晶体结构研究
准晶作为一种非周期性晶体，其独特的晶体结构一直是科学研究的重点。通过对准晶的结构进行深入的研究，有助于我们更好地理解晶体生长的规律和机制。
耐腐蚀材料
准晶具有良好的耐腐蚀性，可应用于化工、海洋工程等领域。在恶劣环境下，准晶材料能够保持较好的稳定性和耐腐蚀性。
准晶在其他领域的应用前景
生物医学领域
准晶材料在生物医学领域具有潜在的应用价值。其生物相容性和独特的物理性质有望用于药物载体、生物成像等方面。
光学领域
准晶具有独特的光学性质，如非线性光学效应。这些性质使得准晶在光学器件、光子晶体等领域具有一定的应用前景。
物理性质研究
准晶表现出许多独特的物理性质，如导电性、热传导性、光学性质等。这些性质与准晶的结构密切相关，通过对这些性质的研究，可以进一步揭示准晶的内在特性。
准晶在材料科学中的应用
超硬材料
准晶具有高的硬度和耐磨性，可以作为超硬材料应用于切削工具、轴承等领域。其优异的力学性能可以提高工具的使用寿命和性能。
准晶简介

准晶特性

Southwest Jiaotong University
西南交通大学
discover of quasicrystal
以色列，以色列，Dan Shechtman 教授准晶被誉为 20 世纪 80 年代凝聚态物理的两大重大进展之一说起准晶，其实质是一种具有长程取向序说起准晶，但无平移对称性材料。本人对“ 但无平移对称性材料。Shechtman 本人对“准这个名字并不赞赏。他后来表示: 晶”这个名字并不赞赏。他后来表示自己并不喜欢这个词．不喜欢这个词．“因为这个词意味着准周期性晶体不是晶体，根据国际晶体学会的新定义，晶体不是晶体，根据国际晶体学会的新定义，它是晶体．但是这个词已经广泛应用了．我它是晶体．但是这个词已经广泛应用了．更喜欢叫它们准周期性材料” 更喜欢叫它们准周期性材料”．
电阻率异常高
西南交通大学
Southwest Jiaotong University
准晶特性
导电特性差别简析：
位于费米能级的伪能隙存在
导电特性
高电阻率
费米能级的电子趋于局域化
Southwest Jiaotong University
西南交通大学
准晶特性
导电特性差别简析：实验发现，准晶的导电性能随样品质量的改善反而降低。准晶异常的导电性能反映准周期结构对物理性能的影响，它可以从准周期系统中电子结构的异常性中得到解释。
准晶材料具有典型的高硬度，高强度。准晶材料具有典型的高硬度，高强度。以镁基准晶为例进行进一步的探讨：以镁基准晶为例进行进一步的探讨：导电特性以色列工业大学和美国国家标准局 NIST ) 将快速凝色列工业大学和美国国家标准局( 色列工业大学和美国国家标准局固镁合金 M g- 5 5Zn- l 5Y-1Ce( - 1Zr) 合金急冷薄带经挤压成形后, 得到了抗拉强度> 过粉碎和 300 挤压成形后得到了抗拉强度 590 MPa, 延伸率约为17% 的超高强度镁合金延伸率约为

准晶体

准晶体的发现与应用摘要:原子呈周期性排列的固体物质叫做晶体，原子呈无序排列的叫做非晶体，准晶是一种介于晶体和非晶体之间的固体。

准晶体具有完全有序的结构，然而又不具有晶体所应有的平移对称性，因而可以具有晶体所不允许的宏观对称性。

物质的构成由其原子排列特点而定。

关键词:准晶体晶体非晶体正文:一. 准晶体的发现准晶体的发现，是20世纪80年代晶体学研究中的一次突破。

1984年底，D.Shechtman等人宣布，他们在急冷凝固的Al Mn合金中发现了具有五重旋转对称但并无平移周期性的合金像，在晶体学及相关的学术界引起了很大的震动。

不久，这种无平移同期性但有位置序的晶体就被称为准晶体。

准晶体准晶体是1982年发现的，具有凸多面体规则外形的，但不同于晶体的固态物质，它们具有晶体物质不具有的五重轴。

如含钬－镁－锌三种金属的准晶体是正十二面体外型。

已知的准晶体都是金属互化物。

2000年以前发现的所有几百种准晶体中至少含有3种金属，如Al65Cu23Fe12，Al70Pd21Mn9等。

但最近发现仅2种金属也可形成准晶体，如Cd57Yb10〔Nature,2000,408:537〕。

有关准晶体的组成与结构的规律仍在研究之中。

有关组成问题值得重视的事实如：组成为Al70Pd21Mn9的是准晶体而组成的Al60Pd25Mn15却是晶体。

有关结构问题，人们普遍认为，准晶体存在偏离了晶体的三维周期性结构，因为单调的周期性结构不可能出现五重轴，但准晶体的结构仍有规律，不像非晶态物质那样的近距无序，仍是某种近距有序结构。

尽管有关准晶体的组成与结构规律尚未完全阐明，它的发现在理论上已对经典晶体学产生很大冲击，以致国际晶体学联合会最近建议把晶体定义为衍射图谱呈现明确图案的固体（any solid having an essentially discrete diffraction diagram）来代替原先的微观空间呈现周期性结构的定义。

第六章准晶材料的制备技术材料制备技术

• (2）热传导特性
• ①与普通金属材料相比，准晶的热导率都很低，在室温下准晶的热导率要比普通的铝合金低两个数量级，可以与常见的隔热材料ZrO2相媲美。
• ②准晶材料的热阻值随着温度升高而下降，即具有负的温度系数，热扩散系数和比热容均随着温度升高而增大。 • ③准晶样品质量越好，结构越完善，其热导性能就越差。 • ④结构复杂的准晶类似相得导热性能接近于准晶。 • （3）光传导特性 • ①与普通的金属材料相比，结构完好的准晶样品的光传导特性，显得非常特殊，在较低的频率范围内，准晶的光导率很小，且在104cm-1时有很宽的峰值。 • ②在二维的准晶材料中，光导率对其结构的各向异性很敏感。
• 6.1.3.2表面特性
• 表面性能主要由其表层的化学成分和原子排列方式所决定，由于准晶表面结构比较独特，由此引发的表面行为如氧化行为、润湿行为和摩擦行为等也与众不同。 • （1）氧化行为特性 • 迄今为止发现的准晶材料，绝大多数为铝系准晶。而Al是极易氧化的活泼元素，因而研究铝基准晶氧化表面的结构和成分的变化规律意义重大。实验研究发现，在相同条件下，准晶相表面的氧化现象明显低于铝合金和相近成分的晶体相。当准晶在室温下长期暴露在干燥空气孔，氧化层平均厚度为2~3nm。但在潮湿空气和较高温度下氧化层会进一步加深（厚度为6~7nm），并且化学成分也因此而变化，表层铝的摩尔分数随之增大（Al可达90％，摩尔分数）。 • （2）不粘特性 • 准晶材料的不粘性，实质上是热力学中润湿性的问题，与准晶的表面能有关。最近的研究发现，准晶的最外层原子没有重构现象和准晶在费米能级处的电子态密度很低（即准晶在费米能级处存在伪能隙）是造成其表面能很低的主要原因。
• （3）摩擦特性 • 准晶材料的摩擦磨损行为的研究相对开展较早，这主要是由于镀膜和热喷涂技术的日臻完善。在相同环境和实验条件下，块体Al-Cu-Fe准晶和其准晶涂层的显微硬度与摩擦系数大致相近，而准晶的显微硬度却要比铝合金高一个数量级，但摩擦系数仅为铝合金的1/3。此外，当对准晶材料进行往复摩擦实验时，其摩擦系数还会逐渐降低，且磨痕上的微裂纹会自动愈合，这显示了准晶具有一定的应力塑性。

《2024年准晶增强Mg97.6Zn1.8Y0.6合金高压凝固及热变形行为》范文

《准晶增强Mg97.6Zn1.8Y0.6合金高压凝固及热变形行为》篇一一、引言金属合金材料是现代工业与科技发展的重要基石，尤其是轻质、高强度的合金，在航空航天、汽车制造、电子设备等领域具有广泛的应用。

近年来，Mg-Zn-Y系合金因其良好的力学性能和加工特性，受到了研究者的广泛关注。

本文以Mg97.6Zn1.8Y0.6合金为研究对象，重点探讨其高压凝固及热变形行为，特别是准晶增强对其性能的影响。

二、材料制备与实验方法本研究中，我们采用高纯度的Mg、Zn和Y元素作为原料，按照特定的比例混合并熔炼制备了Mg97.6Zn1.8Y0.6合金。

通过高压凝固技术，我们成功获得了具有准晶增强结构的合金样品。

实验过程中，我们利用差示扫描量热仪（DSC）和X射线衍射仪（XRD）对合金的凝固过程和相结构进行了分析。

同时，我们还进行了热模拟压缩实验，以研究合金的热变形行为。

三、高压凝固行为分析在高压凝固过程中，Mg97.6Zn1.8Y0.6合金表现出了独特的相变行为。

随着温度的降低和压力的增加，合金中的元素开始发生重排和相变。

准晶相的形成显著影响了合金的凝固过程，使其形成更为细小的晶粒结构。

这一结构有利于提高合金的力学性能和加工性能。

四、热变形行为分析在热模拟压缩实验中，我们发现Mg97.6Zn1.8Y0.6合金展现出显著的流变应力行为。

随着温度的升高和应变速率的降低，合金的流变应力逐渐减小。

这表明在一定的温度和应变速率范围内，合金具有良好的热加工性能。

同时，准晶增强结构在热变形过程中起到了阻碍晶界滑移的作用，提高了合金的抗蠕变性能。

五、结果与讨论通过DSC和XRD分析，我们确定了合金的相组成和晶体结构。

高压凝固过程中形成的准晶相显著细化了晶粒结构，提高了合金的力学性能。

此外，我们还发现准晶相对合金的热稳定性具有重要影响，使其在高温下仍能保持较高的力学性能。

在热变形过程中，准晶增强结构对提高合金的抗蠕变性能起到了关键作用。

准晶、非晶、纳米晶、粗晶、液晶的结构、性能、制备技术及应用(一)

辽宁工程技术大学
材料科学最新进展
题目准晶、非晶、纳米晶、粗晶、液晶
的结构、性能、制备技术及应用指导教师吕宝臣博士
院（系、部）材料科学与工程学院
专业班级材料07-1班
学号0708010108
姓名关媛媛
日期2010年10月17日
教务处印制
目录
前言 (1)
1准晶 (2)
1.1准晶的结构 (2)
1.2准晶的性能 (2)
1.3准晶的制备技术 (2)
1.4准晶的应用 (3)
2非晶 (3)
2.1非晶的结构 (4)
2.2非晶的性能 (4)
2.3非晶的制备技术 (4)
2.4非晶的应用 (5)
3纳米晶 (6)
3.1纳米晶的结构 (6)
3.2纳米晶的性能 (6)
3.3纳米晶的制备技术 (7)
3.4纳米晶的应用 (7)
4粗晶 (8)
4.1粗晶的结构 (8)
4.2粗晶的性能 (8)
4.3粗晶的制备技术 (8)
4.4粗晶的应用 (9)
5液晶 (10)
5.1液晶的结构 (10)
5.2液晶的性能 (10)
5.3液晶的制备技术 (11)
5.4液晶的应用 (12)
致谢 (13)
参考文献 (14)。

准晶晶体材料探讨(doc 18页)

准晶晶体材料研究尹显富内容提要：准晶体结构自1984年被报道以来，因其与传统晶体周期性不相容的特殊结构，引起各国学者的极大兴趣。

对准晶材料性能及应用研究结果表明，准晶材料因独特的结构而具有独特的性能，但由于材料科学迅猛发展，新材料层出不穷，而准晶材料所具有的一些优异的性能，能满足一些实际应用中传统材料所不能满足的要求。

因此，了解其发展历程、掌握其理论基础、研究现状及其发展前景，对于研究开发能应用于实际生活、生产的准晶材料有着重要意义，这是本题的主要内容。

关键词：准晶材料物理性质性能准晶结构The physical properties of quasicrystalline materials and research progressYinXianfuAbstract:Quasi-crystal structure has been reported since 1984, because of its incompatibility with traditional periodic special crystal structure, causing great interest scholars from different countries. Alignment of crystal material properties and applied research results show that because of the unique quasi-crystalline structure of materials with unique properties, but because of the rapid development of materials science, new materials emerging, while the quasi-crystalline material with some of the excellent performance, to meet some practical applications of traditional materials can not meet the requirements. Therefore, understanding the development process, to grasp its theoretical basis, research status and development prospects for the research and development can be applied in real life, the production of quasi-crystalline materials is of great significance, which is the main content for this question.Keywords: Quasicrystal Physical properties Performance Quasicrystals目录绪论准晶材料作为一种新兴材料，自从1982年准晶（Quasicrystal）的发现至今，有关什么是晶体的辩论一直没有中断。

高等物理冶金-准晶

7/5/2021
5
中南大学
材料科学与工程
准晶的分类
(6L510L315L2)
三维准晶原子结构在三维空间场作准周期排列。三维准晶主要
为二十面体型,包含6个5次对称轴、10 个3次对称轴和15个2次对
称轴。
二维准晶原子结构是在主轴方向上呈周期性平移对称,而在与该
主轴正交的平面上呈准周期排列。二维准晶包括8次、10次和12
Al-Mn合金的准晶相:
由一系列取向相同、棱或顶相连接的
20面体结构单元非周期性地连接而成,空
隙由无序分布的原子填充。
面体准点阵的倒易点阵也是一个20面体
20面体12个顶点由Al原子占据,Mn原
子位于20面体中心, Mn与A1原子之间有
。因此，准晶也产生明锐的斑点衍射。
序键合,各20个面体的取向相同。
t
=
5+1
2
序列中: L成单或成双出现, S单个出现;
任意项均为前两项之和;
相邻项的比值逐渐逼近。
7/5/2021
8
中南大学
材料科学与工程
L1
Symmetry in 2D arrangement of atoms
L2
L3
L4
L6
Rotary Symmetries are incompatible with translational periodicity:
7/5/2021
20
中南大学
材料科学与工程
准晶的形成与制备
1、冷凝速度
当熔体快速冷却时, 原子簇无规排列, 便形成非晶态材料;
熔体冷却得很慢, 原子可以扩散, 原子簇之间可协调相互位置,使
其具有长程周期序,便成为晶态相。

2-3-准晶、非晶和液晶PPT课件

准晶态的结构特征
1974年，数学家Penrose提出用两种四边形，夹角分别为：
72o、72o、144o、72o 36o、72o、36o、216o 可以将平面铺满，不留空隙这种图形具有5次对称性彭罗斯铺砌的四边形是将一个菱形切开而得到的：
风筝
飞镖
所得图形到处呈现5次对称性，但没有平移周期性
（3）含La系、Ac系元素的非晶态合金。
典型的非晶态合金： 1、铁基非晶合金；2、铁镍基非晶合金； 3、钴基非晶合金；4、铁基纳米晶合金（超微晶合金）
2.5 性能与应用
a.力学性能：非晶态合金具有极高的强度和硬度，强度远超过晶态高强度钢，σf/E是衡量材料达到理论强度的程度，一般金属晶态材料σf/E约为1/500，而非晶态含量约为 1/50，材料强度利用率大大高于晶态。另外，非晶态合金的抗疲劳度亦很高，如Co基非晶态合金可达1200MPa。但，非晶态合金的延伸率一般较低。已有突破！
以后又陆续发现了具有8次、10次、12次对称的准晶结构。目前在自然界中还没有发现准晶体。
准晶的发现一方面极大地深化了我们对晶体学、衍射物理和凝聚态物理的认识。另一方面，准晶体的各种独特性质使其具有潜在的应用价值。
2021/4/1
4
五次对称性
准晶对称的鱼
二十面体准晶
2021/4/1
五次对称性及Ti-Ni准晶相的发现与研究6
当液体温度降至Tg，粘滞系数成数量级的突变，成为非平衡态的亚稳固体。
冷却速度越高，Tg越高，越有利于非晶态材料的形成
非晶态固体的结构可以用三种不同的模型来描述，它们分别是无规密堆积模型、连续无规网络模型和无规线团模型。
1.无规密堆积模型右图是描述非晶态金属结构

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准晶
什么是准晶？
准晶（Quasicrystal）是一种特殊的晶体结构，不同于常见的周期性晶体。

它以自我复制的方式组成，具有类似于晶体的长程有序性，同时又有类似于非晶体的无规则性。

准晶的发现引起了科学界的广泛关注和研究，对固体物理学和材料科学有着重要的意义。

准晶最早由以色列科学家丹·舍帕斯于1982年发现。

他发现了一种由铝、锰和金属硅组成的合金，其X射线衍射图谱显示出非常奇特的衍射斑点图案。

这种图案既不是晶体的经典单一斑点，也不是非晶体的连续衍射环，而是由固定的五角星图案组成。

这一发现颠覆了当时对晶体结构的认识，开启了准晶研究的新篇章。

准晶的结构特点
准晶的结构特点可以用“离子包络模型”来描述。

这个模型假设准晶中的原子排列类似于离子包络，由环绕原子球组成。

准晶的结构可以通过一组向量来描述，这组向量被称为“母基矢”。

准晶的母基矢不是简单的周期性晶体的矢量，而是具有非周期性和非整数的关系。

这种非晶体的特性使准晶的结构具有五角星、八角星等非传统形状的对称性。

准晶的结构还具有“五重旋转对称性”，即它的结构在沿着某个固定轴旋转180度时仍保持不变。

准晶的应用
准晶的独特结构特点使其具有一些特殊的物理性质和应用价值。

首先，准晶具有低摩擦系数和低热导率的特点，使其在润滑材料和热障涂层等领域有着广泛的应用。

其次，准晶还具有高硬度和高强度的特点，与金属和陶瓷相比具有更好的机械性能。

因此，准晶在材料加工、汽车制造和航空航天等领域的应用也越来越广泛。

此外，准晶还具有优异的电学和光学性能，使其在电子器件和光学器件等领域具有潜在的应用前景。

准晶在导电性能、光学透明度和磁学性能方面都具有特殊的优势，因此对其的研究和应用也成为当前热门的科研领域之一。

准晶的未来
对准晶的研究还处于相对初级的阶段，很多问题仍然待解决。

当前的研究重点主要集中在准晶的合成方法、结构与性质之间的关系以及准晶的制备工艺等方面。

随着科学技术的不断进步，相信对准晶的认识会进一步深化，其潜在的应用领域也将继续扩展。

此外，准晶的研究还有助于拓展对固体物理学和材料科学的认识。

通过研究准
晶结构的规律和特点，可以更好地理解晶体结构的形成机制，为新材料的设计与合成提供更多的启示。

总之，准晶作为一种独特的晶体结构，具有重要的科学意义和广泛的应用前景。

对准晶的研究不仅对材料科学领域具有重要影响，也有助于推动科学技术的进步和发展。

参考文献：
1.Shechtman, D. et al. (1982).。