ch9_noneferrous-有色金属双语

Al
Si
Si shape modified by Sr
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9.1 Aluminum Alloys 9.1.4 Portion of the aluminum-magnesium phase diagram
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Materials for mechanical Engineering
Materials for mechanical Engineering
Non-Ferrous Alloys
Prof. Liuzhang Ouyang
School of Materials Science & Engineering South china University of technology
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9.1 Aluminum Alloys
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9.1 Aluminum Alloys 9.1.2 Al-Cu alloys
• adding Cu lowers the melting point of Al • alloy suitable for casting • Al-Cu alloys can be age hardened (see later)
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9.1 Aluminum Alloys Al-Cu phase diagram
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9.1 Aluminum Alloys Al-4wt%Cu
fine Al2Cu precipitates (age hardened)
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9.1 Aluminum Alloys Al-4wt%Cu
coarse Al2Cu (over aged)
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9.1 Aluminum Alloys 9.1.3 Al-Si alloys • adding Si lowers the melting point of Al • alloy suitable for sand or die casting (high fluidity) • Al and Si have no solid solubility below the eutectic – so obtain microstructure of Si particles in an Al matrix • good corrosion resistance and good weldability • microstructure can be refined by rapid cooling to increase strength and ductility • or modify microstructure by adding Sr
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9.1 Aluminum Alloys 9.1.6 Precipitation Hardening
• • An appreciable maximum solubility of one component in the other, on the order of several percent A solubility limit that rapidly decreases in concentration of the major component with temperature reduction
9.1 Aluminum Alloys 9.1.6 Age (or precipitation) hardening • method of strengthening metals • e.g. Al-Cu, 7075 Al-1.5Cu-2.5Mg-5.5Zn-0.3Mn-0.2Cr-0.5Fe-0.4Si-0.3(Zr+Ti) • Need decrease in solid solubility of an alloying element with decreasing temperature • Draw suitable phase diagram:
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9.1 Aluminum Alloys 9.1.3 Al-Si phase diagram
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9.1 Aluminum Alloys 9.1.3 Sand-cast 443 aluminum alloy
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Non-Ferrous Alloys
Metal Alloys
• Ferrous Alloys: Alloys containing more than 50wt.%Fe – Classification of Steels – Designation of Steels • Nonferrous Alloys: Alloys containing less than 50wt.%Fe – Aluminum – Copper – Magnesium – Titanium – Refractory(难熔) metals – Superalloys（超耐热合金） – Noble metals（贵金属）
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9.1 Aluminum Alloys
9.1.1 Aluminum Alloys
• • • • • • Refined by electrolytic reduction of aluminum oxide Requires a lot of electricity Easy to form and light weight Work hardens well • cast – e.g. Al-Cu, Al-Si Easy to recycle • wrought – e.g. 7000 series alloys Oxidation coating
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9.1 Aluminum Alloys
Production of aluminum in an electrolytic cell
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9.1 Aluminum Alloys
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9.1 Aluminum Alloys 9.1.3 Al-12Si-0.02Sr
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9.1 Aluminum Alloys 9.1.3 Al-12Si-0.02Sr
Chapter Outline
9.1 Aluminum Alloys 9.2 Magnesium and Beryllium Alloys 9.3 Copper Alloys 9.4 Nickel and Cobalt Alloys 9.5 Titanium Alloys 9.6 Bearing alloys
L L+α α A (a) α B A
L β α+β (b) B A
L α β B
α+β (c)
Which of the above systems can be precipitation-hardened? The answer is (c)!
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Non-Ferrous Alloys
Learning objective
1. Explore the properties and applications of Cu, Al, and Ti alloys in load-bearing applications. 2. Designation of nonferrous alloy 3. Age (or precipitation) hardening热处理—时效强化（以 Al-4%Cu为例） 4. Designation of bearing alloys
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Non-Ferrous Alloys
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Non-Ferrous Alloys
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9.1 Aluminum Alloys 9.1.5 Wrought Al alloys • wrought = rolled, extruded, forged – heat treatable – non-heat treatable • International alloy designation system (IADS) – e.g. 1XXX = Al – 7XXX = Al-Zn-Mg-(Cu) – specific example “7075”: Al-1.5Cu-2.5Mg-5.5Zn-0.3Mn-0.2Cr0.5Fe-0.4Si-0.3(Zr+Ti) • NB no universally accepted designation system for cast alloys
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9.1 Aluminum Alloys 9.1.3 Al-wt%12Si
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9.1 Aluminum Alloys 9.1.3 Al-wt%12Si
(a) Sand-cast 443 aluminum alloy containing coarse silicon and inclusions. (b) Permanent-mold 443 alloy containing fine dendrite cells and fine silicon due to faster cooling. (c) Die-cast 443 alloy with a still finer microstructure (× 350).
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9.1 Aluminum Alloys Inclusions and precipitation in aluminum alloy
(a) FeAl3 inclusions in annealed 1100 aluminum (× 350). (b) Mg2Si precipitates in annealed 5457 aluminum alloy (× 75).
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Non-Ferrous Alloys
Non-ferrous Alloys Predate Iron
• Many non-ferrous alloys can be produced at lower temperatures than iron • Copper, brass, and bronze all predate iron alloys
Al
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Si
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9.1 Aluminum Alloys 9.1.3 Al-12Si-0.02Sr
Eutectic composition shifted - so obtain primary silicon dendrites