Photothermal depth profiles of mechanically and electrolytically polished NiTi shape memory alloys (abstract)

Machining of NiTi shape memory alloys (SMA) is difficult due to the required special tools, techniques, and the wear of cutting tools. Thus metal injection molding (MIM) of NiTi powders followed by polishing processes may be an alternative fabrication process for SMA components. Transient heat input across the surface and heat transport inside SMA components are important aspects for their functional efficiency. In this work the influence of polishing processes on the thermal depth profiles of SMA materials and the thermal bulk properties of MIM samples are analyzed with the help of photothermal IR radiometry. The effects of polishing have been studied both for polycrystalline nearly equiatomic NiTi alloy and MIM samples. Bulk samples, cut from a polycrystalline ingot of nearly equiatomic NiTi, had first been heat treated and flash cooled to reduce the concentration of nonequiatomic precipitations. In the second step, sample 1 was polished mechanically with a plane grinder, sample 2 was polished electroch...