Crystallographical Analysis of Martensitic Transformation Observed in Cu-Sn Alloy

Cu-Sn ingot having compositions of Cu -14.5 % at. Sn was prepared by arc melting high–purity (at least 99.9%). The ingot was annealed in an Argonne atmosphere at 1050 °C for 50 h to obtain the β-phase. The austenitic sample was cooled in liquid nitrogen and the martensite phase transformation occurred. Using the rigorous version of the infinitesimal deformation approach in the present work, the crystallographical parameters such as habit plane normal, amount of lattice invariant shear, magnitude of the total shape deformation, orientation relationships between the austenite and martensite phase, etc. associated with Cu-Sn alloy have been predicted from a knowledge only of the lattice parameters of the austenite and final martensite phases. The lattice parameters of the austenite and martensite phases are determined from the experimental studies on Cu-Sn alloy in the present study and the crystallographic features of the martensitic transformation are compared with the values calculated using the approach. The agreement between the calculated and the observed results for this alloy system as well as the others is strong evidence for the applicability of the approach presented in this study to the cubic to the orthorhombic phase transformation observed in this alloy system.