Martensitic Transformation of TiAu Shape Memory Alloys
Martensitic transformation temperatures were measured and transformation strains were evaluated in a promising high temperature shape memory alloy TiAu with a compositional range from 46 to 53mol%Au. It was found by differential scanning calorimetry that martensitic transformation start temperature (Ms) is kept almost constant value of 880K in the Au-rich side of the stoichiometric composition. On the other hand, Ms decreases monotonically with decreasing Au content in the Au-poor side. X-ray diffraction analysis revealed that apparent phase of all the alloys at room temperature is B19 martensite phase. Under an assumption that the atomic volume is constant during martensitic transformation, the lattice parameters of B2 parent phase and maximum transformation strain were calculated. It was found that the maximum transformation strain depends on chemical composition and that it reaches 10.75% for Ti-53mol%Au alloy. The value is comparable to that of Ti-Ni.
Young Won Chang, Nack J. Kim and Chong Soo Lee
H. Hosoda et al., "Martensitic Transformation of TiAu Shape Memory Alloys", Materials Science Forum, Vols. 561-565, pp. 1541-1544, 2007