Martensite fraction-temperature diagram of TiNi wires embedded in an aluminum matrix

The martensite fraction-temperature diagrams of TiNi wires embedded in a pure aluminum matrix were studied by differential scanning calorimetry (DSC) measurement. Results showed that the initial phase constitution at the deformation temperature affects significantly the transformation behaviors of the constrained TiNi wires. However, for all composites with different phase constitution, the DSC curves are similar in the second and following heating cycles, where only one peak appears on each curve that corresponds to the reverse transformation of the self-accommodating martensite. There is always some amount of preferentially oriented martensite left in the TiNi wire, but its reverse transformation cannot be detected by conventional DSC.