Suspended droplet alloying: A new method for combinatorial alloy synthesis; nitinol-based alloys as an example

A new combinatorial alloy synthesis method (suspended droplet alloying) has been developed as a high-throughput approach for alloy discovery. The method is based on using a laser to melt elemental or alloyed wires fed at a controlled rate to achieve a specific chemistry. In this study, the metallurgical characteristics of alloy buttons created using this technique were assessed for TiNi-based shape memory alloy buttons deposited using pure Ni, Ti, and Cu wires. The microstructural and chemical inhomogeneity was assessed using quantitative electron microscopy and X-ray diffraction. Furthermore, the phase transformation temperatures of the coupons have been compared to cast and heat-treated (reference) samples. In general, the samples displayed a limited local deviation from the target chemistry (±1 wt%), while displaying a fairly homogeneous microstructure with the expected phase distribution. Post-process homogenisation heat treatments enhanced the phase transformation response, approaching the response obtained from the reference samples.