1. a) An aluminum alloy used by Tesla to lightweight their vehicles (and thereby increase range per battery charge) has been solution treated at 560 C for 10 minutes, water quenched and then artificially aged at 180 C for 20 minutes during the paint bake cycle. Given the following: The evolution of the radius of precipitates at 180 C is given by: - R2 R = kt where Ro 1.2 nm and k = 5.0x10-23 ms-1. The evolution of the volume fraction of precipitates, f, at 180 C is given by: f = fpeak (1 exp[3t^]) where n = 1,6.0x10 s and fpeak = 0.01 The dependence of the average obstacle strength on precipitate radius is given by: F = kGbR where k = Re = 2.7 nm b Rc (10) Calculate the yield stress of the alloy for this condition. (5) b) The materials characterization lab of your company has measured a grain size of a new high strength low alloy steel to be 1.5 m. They have asked you to provide them with an estimate of the yield stress. You checked around and found that for a similar chemistry, the yield stress of samples with grain sizes of 5 and 30 m was 450 and 300 MPa, respectively. Assuming that you can extrapolate this behavior to smaller grain sizes, please provide and estimate of the yield stress for the material with a grain size of 1.5 m 2