For an impressible, isotropic material, what is its Poisson’s ratio Name: ___________________________ HW of ETM 307 Chapter 10: Al Alloys 70 pts in total For materials science, the essential point is...

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For an impressible, isotropic material, what is its Poisson’s ratio Name: ___________________________ HW of ETM 307 Chapter 10: Al Alloys 70 pts in total For materials science, the essential point is to figure out an effective way to increase materials strength without significantly compromising ductility. When we learned precipitation strengthening, we knew that, for a given amount of an alloying element, fine and uniform-distributed precipitates generated by the alloying element are more efficient in increasing materials strength than the element’s atoms staying as solid solution atoms. We just finished learning the aging treatment of Al alloys, the questions for you are: 1. You are given an equilibrium-solidified Al-Cu alloy indicated in Figure 1. Please advise a heat treatment procedure that can be used to achieve a maximum strength without losing a significant amount of ductility. Please draw your temperature history in the temperature-time coordinate beside the phase diagram and describe the microstructure change in each heat treatment step. (40 pts) C 548 o 2. What is precipitate-free zone? How does it form? How to get rid of it? (20 pts) 3. There are heat treatable and non-heat treatable Al alloys. What makes this difference? (10 pts) Copper (wt.%) Temperature (°C) � EMBED Equation.3 ��� � EMBED Equation.3 ��� � EMBED Equation.3 ��� � EMBED Equation.3 ��� � EMBED Equation.3 ��� � EMBED Equation.3 ��� � EMBED Equation.3 ��� � EMBED Equation.3 ��� � EMBED Equation.3 ��� � EMBED Equation.3 ��� � EMBED Equation.3 ��� � EMBED Equation.3 ��� � EMBED Equation.3 ��� � EMBED Equation.3 ��� � EMBED Equation.3 ��� � EMBED Equation.3 ��� � EMBED Equation.3 ��� Temperature (°C) Time � EMBED Equation.3 ��� Fig.1 MSU, Qingzhou Xu q a + a + L L 800 600 400 200 0 20 30 40 60 10 50 0 ) ( 2 q CuAl a C 548 o q a + a + L L 800 600 400 200 0 20 30 40 60 10 50 ) ( 2 q CuAl a _1363676364.unknown _1363676840.unknown _1363676993.unknown _1363677064.unknown _1363700595.unknown _1365408468.unknown _1363677016.unknown _1363676983.unknown _1363676988.unknown _1363676951.unknown _1363676405.unknown _1363676430.unknown _1363676383.unknown _1253520234.unknown _1363676333.unknown _1253520232.unknown _1253520231.unknown