(a) Age hardening is used to strengthen the Al-4wt% Cu alloy. Part of the equilibrium phase...

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(a) Age hardening is used to strengthen the Al-4wt% Cu alloy. Part of the equilibrium phase diagram for the binary Al-Cu system is reproduced in Figure Q1 for your information. i) Describe and explain the purpose of each stage of the age hardening procedure. ii) Describe the microstructural changes which take place during all stages of the heat treatment, and explain why these lead to increased yield strength. iii) Explain why over-ageing leads to decrease in strength. (b) The basic phases of Ti alloys are a (hcp) and B (bcc). What are the main characteristics of each of these two phases? What properties make Ti-6Al- 4V, an a+ alloy, widely used? (c) Creep resistance is a main consideration in developing turbine blades in aero engines. Draw and annotate a schematic constant-load creep strain curve typical of metals, pointing out the most important characteristics. What microstructural and physical characteristics of an alloy make it resistant to creep? Temperature (C) 700 600 500 400 300- 200 100 Al -4% alloy 10 0.1% 20 4+D 30 Weight % Cu 40 50 Figure Q1 Part of phase diagram for Al-Cu system 8 (CuAl) 60 (a) Age hardening is used to strengthen the Al-4wt% Cu alloy. Part of the equilibrium phase diagram for the binary Al-Cu system is reproduced in Figure Q1 for your information. i) Describe and explain the purpose of each stage of the age hardening procedure. ii) Describe the microstructural changes which take place during all stages of the heat treatment, and explain why these lead to increased yield strength. iii) Explain why over-ageing leads to decrease in strength. (b) The basic phases of Ti alloys are a (hcp) and B (bcc). What are the main characteristics of each of these two phases? What properties make Ti-6Al- 4V, an a+ alloy, widely used? (c) Creep resistance is a main consideration in developing turbine blades in aero engines. Draw and annotate a schematic constant-load creep strain curve typical of metals, pointing out the most important characteristics. What microstructural and physical characteristics of an alloy make it resistant to creep? Temperature (C) 700 600 500 400 300- 200 100 Al -4% alloy 10 0.1% 20 4+D 30 Weight % Cu 40 50 Figure Q1 Part of phase diagram for Al-Cu system 8 (CuAl) 60

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This question is about materials science focusing on age hardening or precipitation hardening the properties of titanium alloys and the creep resistance of materials Lets address each part of the ques... View the full answer