https://doi.org/10.15255/KUI.2018.037
Published: Kem. Ind. 68 (3-4) (2019) 111–118
Paper reference number: KUI-37/2018
Paper type: Original scientific paper
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The Influence of Heat Treatment on Microstructure and Phase Transformation Temperatures of Cu-Al-Ni Shape Memory Alloy

I. Ivanić, S. Kožuh, T. Holjevac Grgurić, B. Kosec and M. Gojić

Abstract

This paper presents the results of thermal and microstructural analysis of Cu-Al-Ni shape memory alloy before and after heat treatment. After casting, a bar of Cu-12.8 Al-4.1 Ni (wt.%) alloy, obtained by the vertical continuous casting technique, was subjected to a certain heat treatment procedure. Solution annealing was performed at 850 °C for 60 min, followed by water quenching. Tempering was then performed at four different temperatures (150 °C, 200 °C, 250 °C and 300 °C). The microstructural results were obtained by optical and scanning electron microscopy. Thermodynamic calculation of ternary Cu-Al-Ni system under equilibrium was performed using Thermo-Calc 5 software. Phase transformation temperatures were determined by differential scanning calorimetry (DSC). The DSC results show the highest values of transformation temperatures in as-cast state. After solution annealing and tempering, the transformation temperatures show lower values with exceptional stability of M_s temperature (martensite start temperature).

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Keywords

shape memory alloy, Cu-Al-Ni, heat treatment, phase transformation, microstructure