Microstructural characterization of Cu82.3Al8.3Mn9.4 shape memory alloy after rolling

Mirko Gojić,Borut Kosec,Omer Beganović,Magdalena Selanec,Ivana Ivanić,Stjepan Kožuh,Diana Ćubela,Tamara Holjevac Grgurić

doi:10.30544/314

Abstract

In this paper, the microstructure of Cu82.3Al8.3Mn9.4 (in wt. %) shape memory alloy after hot and cold rolling was investigated. The Cu82.3Al8.3Mn9.4 alloy was produced by a vertical continuous casting method in the form a cylinder rod of 8 mm in diameter. After the casting, hot and cold rolling was performed. By hot rolling a strip with a thickness of 1.75 mm was obtained, while by cold rolling a strip with a thickness of 1.02 mm was produced. After the rolling process, heat treatment was performed. Heat treatment was carried out by solution annealing at 900 °C held for 30 minutes and water quenched immediately after heating. The microstructure characterization of the investigated alloy was carried out by optical microscopy (OM), scanning electron microscopy (SEM) equipped with a device for energy dispersive spectroscopy (EDS). Phase transformation temperatures and fusion enthalpies were determined by differential scanning calorimetry (DSC) method. The homogenous martensite microstructure was confirmed by OM and SEM micrographs after casting. During rolling the two-phase microstructure occurred. Results of DSC analysis showed martensite start (Ms), martensite finish (Mf), austenite start (As) and austenite finish (Af) temperatures.

Highlights

Shape memory alloys (SMAs) are relatively new metallic materials which show the ability to return to some previously defined shape when subject to the appropriate treatment
Crystals are further deformed in the direction of deformation as well as β crystals that still show an additional transformation in martensite of a smaller or greater extent
Austenitic transformation becomes wider after heat treating of the 82.3Cu-8.3Al-9.4Mn sample at 900 °C for 30 minutes and quenching in the water, and it starts at significantly lower temperatures, with austenite start (As) = 28.85 °C and austenite finish (Af) = 50.56 °C

Summary

Introduction

Shape memory alloys (SMAs) are relatively new metallic materials which show the ability to return to some previously defined shape when subject to the appropriate treatment. The microstructure of continuously casted Cu82.3Al8.3Mn9.4 shape memory alloys after hot and cold rolling as well as after heat treatment (quenching and aging) was compared. The hot rolled strips with a thickness of 1.75 mm were heated at 880 °C for 1 minute and cold rolled.

Results

Conclusion