材料科学基础英文版课件
合集下载
2材料科学基础英文版课件_(9)
Impact Fracture Testing (9)
Factors affecting the DBTT
• Strengthening: solid-solution strengthening, precipitation strengthening, and strain hardening (yield strength increase) DBTT increase – hardening embrittlementຫໍສະໝຸດ TICT1 T2 T3
T4
Temperature
Effects of impurity segregation and strengthening on the DBTT
Also read the paper:
S.-H. Song, J. Wu, L.-Q. Weng, and Z.-X. Yuan, “Fractographic changes caused by phosphorus grain boundary segregation for a low alloy structural steel”, Materials Science and Engineering A 497 (2008) 524-527.
• Grain boundary segregation of impurities: segregation of impurities such as P, S, Sn and Sb Grain boundary cohesion decrease DBTT increase – non-hardening embrittlement
Carbon content Strength DBTT and upper shelf energy
材料科学基础英文版课件_(12)
= ~3.810-4
For most metals, the value near the melting point is in the range of 10-3 to 10-4
Chapter 5
Imperfections in Solids
Lecturer: Shenhua SONG
Outline
• Point defects • Linear defects • Plane defects
1. Point defects in metals 2. Point defects in ceramics
Formation – leading to an increase of internal energy – free energy increase (G = H - TS, H=U+PV, U - H - G ) Formation – leading to an increase of entropy (randomness) –free energy decrease At a given temperature, there must be a concentration of point defects at which the free energy of the system has a minimum value.
equilibrium for a certain amount of material and N is the total number of atomic sites
Point Defects – Point Defects in Metals (6)
~3 for most metals e.g. iron (Fe): Hv is ~1.4 eV per atom, the melting points is 1808K (1535oC), the equilibrium vacancy concentration is
skja_03 Fundamentals of Crystallography 材料科学基础(英文课件)
2020/7/3
Seven Crystal Systems
Triclinic
Monoclinic
Orthorhombic Tetragonal Cubic Hexagonal Rhombohedral
a≠b≠c ，α≠β≠γ≠90° a≠b≠c ， α＝β＝90°≠γ
α＝γ＝90°≠β a≠b≠c ，α＝β＝γ＝90° a＝b≠c ，α＝β＝γ＝90° a＝b＝c ，α＝β＝γ＝90° a＝b≠c ，α＝β＝90°γ＝120°
5. Draw a primitive cell for BCC lattice.
Thank you !
3
2020/7/3
We identify 14 types of unit cells, or Bravais lattices, grouped in seven crystal systems.
2020/7/3
Ⅰ.Seven crystal systems
All possible structure reduce to a small number of basic unit cell geometries. ① There are only seven, unique unit cell shapes that can be stacked together to fill three-dimensional. ② We must consider how atoms can be stacked together within a given unit cell.
120o
120o 120o
c
a ba
2020/7/3
Examples and Discussions
Seven Crystal Systems
Triclinic
Monoclinic
Orthorhombic Tetragonal Cubic Hexagonal Rhombohedral
a≠b≠c ，α≠β≠γ≠90° a≠b≠c ， α＝β＝90°≠γ
α＝γ＝90°≠β a≠b≠c ，α＝β＝γ＝90° a＝b≠c ，α＝β＝γ＝90° a＝b＝c ，α＝β＝γ＝90° a＝b≠c ，α＝β＝90°γ＝120°
5. Draw a primitive cell for BCC lattice.
Thank you !
3
2020/7/3
We identify 14 types of unit cells, or Bravais lattices, grouped in seven crystal systems.
2020/7/3
Ⅰ.Seven crystal systems
All possible structure reduce to a small number of basic unit cell geometries. ① There are only seven, unique unit cell shapes that can be stacked together to fill three-dimensional. ② We must consider how atoms can be stacked together within a given unit cell.
120o
120o 120o
c
a ba
2020/7/3
Examples and Discussions
材料科学基础双语课件
control the material properties (for example by altering the
grain structure, or the presence of defects in the atom
packing) or to fabricate the material into the desired shape.
extra material, joining parts (e.g., by soldering or welding),
forming (forging, rolling, bending, etc.), or compacting particles which are then fused together (sintering, used for
gases (and most engineering materials are used in solid
form).
1.1 What is Materials Science and Engineering?
It may seem abstract and remote from real engineering to
The Science and Engineering of Materials
Aim
English atmosphere: speaking, reading, writing and lisห้องสมุดไป่ตู้ening; Specialty vocabulary; Specialty knowledge;
form. As this mixture solidifies, different structures form as a function of temperature. The phase diagrams that provide
grain structure, or the presence of defects in the atom
packing) or to fabricate the material into the desired shape.
extra material, joining parts (e.g., by soldering or welding),
forming (forging, rolling, bending, etc.), or compacting particles which are then fused together (sintering, used for
gases (and most engineering materials are used in solid
form).
1.1 What is Materials Science and Engineering?
It may seem abstract and remote from real engineering to
The Science and Engineering of Materials
Aim
English atmosphere: speaking, reading, writing and lisห้องสมุดไป่ตู้ening; Specialty vocabulary; Specialty knowledge;
form. As this mixture solidifies, different structures form as a function of temperature. The phase diagrams that provide
2材料科学基础英文版课件_(12)
• Deformation-induced nonequilibrium vacancies
Point Defects – Point Defects in Metals (4)
The molar free energy of the crystal containing Xv mole of vacancies:
பைடு நூலகம்• There is always some level of impurity or foreign atoms in a metal, leading to the formation of an alloy
• Alloys – solid solutions and intermetallics • Concept: solvent – the matrix or host; solute
• Thermal equilibrium vacancies and interstitials
• Quenching-induced nonequilibrium vacancies and interstitials
• Irradiation-induced nonequilibrium vacancies and interrstitials
Point Defects – Point Defects in Metals (1)
1. Vacancies and Interstitials (self-interstitials)
Frenkel pair: vacancy + interstitial
Schottky defect: moving an atom to the surface produces a vacancy
Point Defects – Point Defects in Metals (4)
The molar free energy of the crystal containing Xv mole of vacancies:
பைடு நூலகம்• There is always some level of impurity or foreign atoms in a metal, leading to the formation of an alloy
• Alloys – solid solutions and intermetallics • Concept: solvent – the matrix or host; solute
• Thermal equilibrium vacancies and interstitials
• Quenching-induced nonequilibrium vacancies and interstitials
• Irradiation-induced nonequilibrium vacancies and interrstitials
Point Defects – Point Defects in Metals (1)
1. Vacancies and Interstitials (self-interstitials)
Frenkel pair: vacancy + interstitial
Schottky defect: moving an atom to the surface produces a vacancy
材料科学基础英文版课件（ＰＤＦ）
Law • Steady State: the concentration profile doesn't
change with time.
Steady State:
J x(left)
J x(right) J x(left) = J x(right)
x
Concentration, C, in the box doesn’t change w/time.
Non Steady State Diffusion
• Concentration profile,
dx
C(x), changes with time. J (left)
J (right)
• To conserve matter:
J (right)
− J (left)
=
dC −
dx
dt
dJ = − dC
ΔJ y
=
− ∂J y ∂y
dxdydzδt
ΔJ z
= − ∂J z ∂z
dxdydzδt
对整个元体积：
−
⎜⎜⎝⎛
∂J x ∂x
+
∂J y ∂y
+
∂J z ∂z
⎟⎟⎠⎞dxdydzδt
若 δt 时间内粒子浓度变化δc ，则在dxdydz
元体积中粒子变化为
δcdxdydz
∴ ∂c ∂t
=
−⎜⎜⎝⎛
∂J x ∂x
Fick’s Second Law
δt 时间内沿x方向扩散
元体积dxdydz
流入的粒子数： J x dydzδt
流出的粒子数：
(J x
+
∂J x ∂x
dx)dydzδt
skja_06CrystallographicFormulas材料科学基础英文课件
(u1a)2 (v1b)2 (w1c)2 (u2a)2 (v2b)2 (w2c)2
For hexagonal: cos
u1u2
v1v2
w1w2
(
c a
)2
1 2
(u1v2
u2v1)
u12
v12
w12
(
c a
)2
u1v1
u22
v22
w22
(
c a
)2
u2v2
10. The volume of unit cells V
材料科学基础
Fundamental of Materials
Prof: Tian Min Bo
Tel: 62795426 ，62772851 E-mail: tmb@ Department of Material Science and Engineering Tsinghua University. Beijing 100084
For hexagonal crystals:
1 d2
4 3
h2
hk a2
k2
l2 c2
7. The length of [u v w]
L[uvw] (ua )2 (vb )2 (wc )2 2vwbccos 2uwac cos 2uvabcos
For cubic: L[uvw] a u2 v2 w2
For simple cubic (001) aaaa…… (110) abab……
shift 1 [1 10], along [1 10] 2
This sequence is called the stacking order
Ⅱ.Comparison of stacking mode of HCP and FCC
材料科学基础英文版课件-(13)
Ductility
The ability of a material to be stretched without breaking.
Toughness
The ability of a material to absorb energy before fracturing.
Physical Properties
Some common examples of polymers include plastic, rubber, and fiberglass.
Polymers can be natural or synthetic.
Composites
Composites are materials that consist of two or more materials with different physical and chemical properties.
Nondestructive testing techniques: 超声波检测，射线检测，涡流检测等 。
02
Materials Properties
Mechanical Properties
Elasticity
The ability of a material to return to its original shape after being deformed by an external force.
Metals
Metals are materials that are typically ductile, malleable, and conduct electricity well.
They are often used in the manufacturing of various
材料科学基础英文版课件_(11)
d
e
g
f
7c/8
(2/3,1/3,3/4)
dae a
Ro = a2/2 – R
= 2R – R =
g
f
0.414R (a=2R)
(2/3,1/3,7/8)
Rt = (3/8)c – R = (3/8)x1.633a –R = 0.225R (a=2R)
Metallic crystal structures (11)
Metallic crystal structures (7)
3) Hexagonal close-packed (HCP) crystal structure
Each unit cell contains 6 atoms (12(1/6) + 2(1/2) + 3 = 6)
2R = a R = a/2
Two other features: coordination number (CN) and atomic packing factor (APF) CN: the number of nearest-neighbour atoms – 12 for FCC APF: the fraction of atom-occupied volume in a unit cell
4.2198 10-22 g Unit cell volume = a3 = (0.36148)3 = 0.04723 nm3 = 4.7234 10-23 cm3 = (weight of atoms in each unit cell)/unit cell voulme = 4.2198 10-22
CN = 12 c/a = ? APF = ?
Equilateral triangle
skja_26 Diffusion in Solids 材料科学基础(英文课件)
0t0 , t1来自t2 t增加r2 r1
r1
r2 r
2020/10/25
Application to crystallization at initial stage.
d d m t 4 π D (C o r 2 C r 1 L )r 1 r 2 4 π r 1 2 D (C o r 1 C L )
C t D2 xC 2 2 yC 22 zC 2D2C
1. In Cartesian coordination system
C (D C )(D C )(D C ) t x x y y z z ifD con s C tt .D ( 2 xC 2 2 yC 2 2 zC 2)
2020/10/25
0
r 2 C 0 r
ca b r
c1
a r1
b
c2
a r2
b
a
(C2 r2
C1 r1
)r1r2
d d m t D d d C rA D 4 r 2 d d C r 4 D (C r 2 2 C r 1 1 )r 1 r 2
2020/10/25
T
T0
AC C 0
B
C
C C C0 C
dm(4r12dr1)(CL
CL)
4r12D(C
CL r1
)dt
(CL
CL)dr1
D(CL C r1
)dt
r12
2D( CL C )t CL CL
2020/10/25
Example
A 0.05cm layer of MgO is deposited between layers of Ni and Ta to provide a diffusion barrier that prevents reactions between the two metals. At 1400℃, Ni ions are created and diffuse through the MgO ceramic to the Ta. Determine the number of nickel ions that pass through the MgO per second. The diffusion coefficient of Ni ions in MgO is 9×10-12cm2/s, and the lattice parameter of nickel at 1400℃ is 3.6×10-8cm.
材料科学基础英文版课件3.6
We could then use 2 values for any of the peaks to calculate the interplanar spacing and thus the lattice parameter. Picking peak 8: 2 = 59.42º or = 29.71º (400)
3/23/2013 4
0°
S
30°
90°
° 120
中南大学
材料科学与工程
ExampleDiffraction
The results of a XRD experiment using x-rays with = 0.7107 Å (a radiation obtained from molybdenum target) show that diffracted peaks occur at the 2 angles as shown in the table. Determine the crystal structure: the indices of the plane producing each peak the lattice parameter of the material
Peak 1 2 3 4 5 6 7 8
2
20.20 28.72 35.36 41.07 46.19 50.90 55.28 59.42
3/23/2013
5
中南大学
材料科学与工程
Example 3.20
2d sin a h2 k 2 l2
SOLUTION
a h2 k 2 l 2 ) sin
T2
a1
a2
fcc: 4 atoms per UC
2材料科学基础英文版课件_
• Stress-induced non-equilibrium grain boundary
segregation – Introduction, experiment, results and discussion,
summary
• Conclusions
2019/9/24
Outline (1)
Ingot
Block 1
Sample processing and pretreatment
Pretreated samples
Aging at different temperatures for different times and quenching
Machining
2019/9/24
Experiment (2)
Applied stress
2019/9/24
2.25Cr1Mo steel
Outline (1)
• Equilibrium grain boundary segregation
– Segregation of phosphorus and molybdenum
• Introduction, experiment, results and discussion, summary
520℃
2019/9/24
Time
Heat treatment procedure
Experiment (4)
Auger electron spectrometer
2019/9/24
Auger specimen
Experiment (5)
2019/9/24
AES scanning position
– Effect of phosphorus grain boundary segregation on intergranular fracture
segregation – Introduction, experiment, results and discussion,
summary
• Conclusions
2019/9/24
Outline (1)
Ingot
Block 1
Sample processing and pretreatment
Pretreated samples
Aging at different temperatures for different times and quenching
Machining
2019/9/24
Experiment (2)
Applied stress
2019/9/24
2.25Cr1Mo steel
Outline (1)
• Equilibrium grain boundary segregation
– Segregation of phosphorus and molybdenum
• Introduction, experiment, results and discussion, summary
520℃
2019/9/24
Time
Heat treatment procedure
Experiment (4)
Auger electron spectrometer
2019/9/24
Auger specimen
Experiment (5)
2019/9/24
AES scanning position
– Effect of phosphorus grain boundary segregation on intergranular fracture
- 1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。
The arrangement of atoms or molecules which actually exists in a crystal • Objective
• Contrived, abstract geometrical array • Geometrical point
• Physical object
= 360/n, n: fold of axis
26
n=2, twofold rotation axis
n=4, fourfold rotation axis
Centre of Symmetry
24
② Mirror Plane (P/m) —— Reflect
Two halves of a molecule can be interconverted by carrying out the imaginary process of reflection across the mirror plane.
2) Point Symmetry
Character:
• The external appearance of crystals is the confining geometry with flat bounding planes which intersect at characteristic angles. • Macroscopic symmetry of crystals reflects the symmetry of space lattice.
• Crystal Structure = The periodic arrangement of atoms in the crystal.
11
? =
=
?
Lattice: Periodic repeating array
12
Lattice, Basis, Crystal Structure
♪ Don't mix up atoms with lattice points ♪ Lattice points are infinitesimal points in space ♪ Atoms are physical objects
Chapter 1
Fundamental Concepts of Crystal
1
1-1. Basic Concepts of Crystal
1) Definition of Crystal
• What is Crystal？ • Crystal and Amorphous
2
• People realized that there are two kinds of mineral in nature: Crystal and Amorphous. • Are there some commonness for crystals? • Regular external shapes, flatgeometric face
1) Symmetry
the regular repeating of equivalence, or identity among constituents of an entity.
R & L Hand： Minor Electric Fan: 120°
Rotor
Symmetric condition ① equivalent or identical parts of an entity ② recurrence through a specific action 19
晶体是内部质点在三 维空间呈周期性重复 排列的固体；或者说， 晶体是具有格子构造 的固体。
8 8
2) Space Lattice and Equivalent Points
Equivalent Point: Identical Surroundings the grouping of lattice points about any given point is identical to the grouping about any other point in the lattice.
•面网密度：dot number in unit area •面网间距：distance between two nets.
• 面网密度大的面网其面 网间距也大
16
（4）Space Lattice 空间格子
联结分布在三维空间内的结点—— Space Lattice 空间格子
• 由三个不共面的行列就可决定一个空间格子
(mirror plane)
Chirality Object
25 25
③ Rotation Axis (Ln / n) —— Rotate
Rotation about the axis by 360/n degrees give an identical orientation and the operation is repeated n times before the original configuration is regained.
♪ Lattice Points do not necessarily lie at the centre of atoms
13
Differences of Lattice and Crystal Structure
Lattice
An array of points in space
Crystal Structure
• Space lattice with 3D period repeating pattern
is built by abstraction equivalent point in crystal structure, which shows .
periodic array of points in three dimension —— Space Lattice
(1) Lattice point (dot) 结点 (2) One dimension array 行列 在空间点阵中，分布在同一直线上的结点构成一个行列。 空间点阵中，任意两个结点连接起来就是一条行列方向。 行列中两个相邻结点间的距离 ——distance between lattice points 结点间距 • 在同一行列中结点间距是相等的； • 在平行的行列上结点间距是相等的； • 不同的行列，其结点间距一般是不等的（某些方向的行 列结点分布较密；另一些方向行列结点的分布较疏。）
空间格子由一系列 平行重叠的平行六 面体构成
17
4) Properties of Crystals
Crystallizing Uniformity Anisotropy Confining Geometry Symmetry Lowest Energy
18
1-2.Symmetry of Crystals
21
3) Symmetry Operations & Symmetry Elements
(1) Symmetry operations
22
（2）Symmetry elements
Symmetry elements— Point, line, plane
Rotation axis Mirror plane Corresponding Symmetry elements ———————— Symmetry operations
20
Symmetry
Snowflake
flowers
Imagine an axis passing through the center of the snowflake, if the snowflake is rotated through 1/6 of a revolution, then the new position is indistinguishable from the old.
Question: • Why many rounded stones and man-made cast solid objects with no external evidence are observed?
7
Definition of crystal
Crystals are built up of regular arrangements of atoms, molecules or ions in three dimensions.
Cleaving a crystal of rocksalt
6
• The external appearance of crystals are all characterized by flat bounding planes which intersect at characteristic angles.
• atoms or ions
A space lattice is a geometrical abstraction which is a reference in describing and correlating symmetry of actual crystals.
14
3) Lattice Elements 空间点阵的要素
Quartz
• The crystal firstly found was quartz with regular shape.
• Quartz with geometrical polyhedron shape was called as crystal.
3
• Later, all solids with geometrical polyhedron shape were defined crystal, such as salt, calcite, magnetite.
• Contrived, abstract geometrical array • Geometrical point
• Physical object
= 360/n, n: fold of axis
26
n=2, twofold rotation axis
n=4, fourfold rotation axis
Centre of Symmetry
24
② Mirror Plane (P/m) —— Reflect
Two halves of a molecule can be interconverted by carrying out the imaginary process of reflection across the mirror plane.
2) Point Symmetry
Character:
• The external appearance of crystals is the confining geometry with flat bounding planes which intersect at characteristic angles. • Macroscopic symmetry of crystals reflects the symmetry of space lattice.
• Crystal Structure = The periodic arrangement of atoms in the crystal.
11
? =
=
?
Lattice: Periodic repeating array
12
Lattice, Basis, Crystal Structure
♪ Don't mix up atoms with lattice points ♪ Lattice points are infinitesimal points in space ♪ Atoms are physical objects
Chapter 1
Fundamental Concepts of Crystal
1
1-1. Basic Concepts of Crystal
1) Definition of Crystal
• What is Crystal？ • Crystal and Amorphous
2
• People realized that there are two kinds of mineral in nature: Crystal and Amorphous. • Are there some commonness for crystals? • Regular external shapes, flatgeometric face
1) Symmetry
the regular repeating of equivalence, or identity among constituents of an entity.
R & L Hand： Minor Electric Fan: 120°
Rotor
Symmetric condition ① equivalent or identical parts of an entity ② recurrence through a specific action 19
晶体是内部质点在三 维空间呈周期性重复 排列的固体；或者说， 晶体是具有格子构造 的固体。
8 8
2) Space Lattice and Equivalent Points
Equivalent Point: Identical Surroundings the grouping of lattice points about any given point is identical to the grouping about any other point in the lattice.
•面网密度：dot number in unit area •面网间距：distance between two nets.
• 面网密度大的面网其面 网间距也大
16
（4）Space Lattice 空间格子
联结分布在三维空间内的结点—— Space Lattice 空间格子
• 由三个不共面的行列就可决定一个空间格子
(mirror plane)
Chirality Object
25 25
③ Rotation Axis (Ln / n) —— Rotate
Rotation about the axis by 360/n degrees give an identical orientation and the operation is repeated n times before the original configuration is regained.
♪ Lattice Points do not necessarily lie at the centre of atoms
13
Differences of Lattice and Crystal Structure
Lattice
An array of points in space
Crystal Structure
• Space lattice with 3D period repeating pattern
is built by abstraction equivalent point in crystal structure, which shows .
periodic array of points in three dimension —— Space Lattice
(1) Lattice point (dot) 结点 (2) One dimension array 行列 在空间点阵中，分布在同一直线上的结点构成一个行列。 空间点阵中，任意两个结点连接起来就是一条行列方向。 行列中两个相邻结点间的距离 ——distance between lattice points 结点间距 • 在同一行列中结点间距是相等的； • 在平行的行列上结点间距是相等的； • 不同的行列，其结点间距一般是不等的（某些方向的行 列结点分布较密；另一些方向行列结点的分布较疏。）
空间格子由一系列 平行重叠的平行六 面体构成
17
4) Properties of Crystals
Crystallizing Uniformity Anisotropy Confining Geometry Symmetry Lowest Energy
18
1-2.Symmetry of Crystals
21
3) Symmetry Operations & Symmetry Elements
(1) Symmetry operations
22
（2）Symmetry elements
Symmetry elements— Point, line, plane
Rotation axis Mirror plane Corresponding Symmetry elements ———————— Symmetry operations
20
Symmetry
Snowflake
flowers
Imagine an axis passing through the center of the snowflake, if the snowflake is rotated through 1/6 of a revolution, then the new position is indistinguishable from the old.
Question: • Why many rounded stones and man-made cast solid objects with no external evidence are observed?
7
Definition of crystal
Crystals are built up of regular arrangements of atoms, molecules or ions in three dimensions.
Cleaving a crystal of rocksalt
6
• The external appearance of crystals are all characterized by flat bounding planes which intersect at characteristic angles.
• atoms or ions
A space lattice is a geometrical abstraction which is a reference in describing and correlating symmetry of actual crystals.
14
3) Lattice Elements 空间点阵的要素
Quartz
• The crystal firstly found was quartz with regular shape.
• Quartz with geometrical polyhedron shape was called as crystal.
3
• Later, all solids with geometrical polyhedron shape were defined crystal, such as salt, calcite, magnetite.