Changes in microstructure of a shape memory alloy (bi-crystal of austenitic CuAlNi )

Changes in microstructure of a shape memory alloy being heat treated and also mechanically deformed. A bi-crystal of austenitic CuAlNi is cooled, causing transformation to the martensitic (2H orthorhombic) phase. The process is reversed in the second half of the video, as the specimen is heated again. The rate at which transformation occurs is controlled by heat flow effects. (The shear process itself tends to take place very rapidly.) The martensitic phase is internally twinned. This is very clear within t