Enhancing Microstructural and Thermal Properties of Tinipd Shape Memory Alloys Through Copper Addition

This study explores how the addition of copper (Cu) addition impacts the microstructural and thermal properties of shape memory alloys (SMAs), specifically TiNiPd alloys. Two compositions, 0Cu and 10Cu, were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), Optical Microscopy (OM) and differential scanning calorimetry (DSC). SEM revealed second-phase precipitates distributed along grain boundaries in both alloys, with sizes ranging from 0.9 to 2.9 μm; however, Cu addition reduced precipitate density without affecting size. The grain size increased significantly from 12.5 μm in 0Cu to 17.5 μm in 10Cu, attributed to decreased nickel content and reduced pinning effects of precipitates. Aging at 600°C and 700°C further influenced precipitate behavior and transformation temperatures, with Cu-containing alloys demonstrating enhanced thermal characteristics. DSC analysis indicated significant increases in transformation temperatures and decreased thermal hysteresis with Cu addition. These results highlight the promise of Cu as a viable substitute for Ni in enhancing the properties of TiNiPd SMAs.