한국주조공학회

For the fabrication of bulk near-net-shape Ti-Ni-Cu shape memory alloys, consolidation of Ti-Ni- Cu alloy powders are useful because of their brittle property. In the present study, Ti50Ni30Cu20 shape memory alloy powders were prepared by gas atomization and martensitic transformation temperatures and microstructures of those powders were investigated as a function of powder size. The size distribution of the powders was measured by conventional sieving, and sieved powders with the specific size range of 25 to 150 μm were chosen for this examination. XRD analysis showed that the B2-B19 martensitic transformation occurred in the powders. In DSC curves of the as-atomized Ti50Ni30Cu20 powders as a function of powder size, only one clear peak was found on each cooling and heating curve. The martensitic transformation start temperature(Ms) of the 25-50 μm powders was 31.5oC. The Ms increased with increasing powder size and the difference of Ms between 25-50 μm powders and 100-150 μm powders is only 1oC. The typical microstructure of the rapidly solidified powders showed cellular morphology and very small pores were observed in intercellular regions.

Ti-Ni-Cu shape memory alloy, Gas atomization, Rapidly solidified powder, Martensitic transformation.