A modified vacuum induction melting technique with argon backfilling to produce pristine Ni–Ti–Si ternary shape memory alloys

Abstract

This research investigates the effect of silicon (Si) addition on the phase transformation behaviour of the Ni–Ti alloy. The Ni–Ti–Si alloys were fabricated with varying proportions of Si through a modified vacuum induction melting technique with argon backfilling. Scanning electron microscopy, X-ray diffraction and differential scanning calorimetry were done to analyse the microstructure, elemental composition, and phase transformation temperatures, respectively, to validate the effectiveness of this modified melting technique. The results indicate an increase in the phase transformation temperature with an increase in the Si content in the alloy mixture and the alloys were prepared with a very minimal amount of detrimental impurities. This technique helps to produce high-temperature shape memory alloys with utmost purity which helps in retaining their functional properties. The transformation temperatures observed from differential scanning calorimetry revealed that the A_f temperature varies from 342.68 K to 379.95 K for 3 to 12% variation in Si content. This group of shape memory alloys have potential use as actuators in aircrafts and various other applications.

Graphical Abstract