Investigation of Microstructure and Tensile Properties of CuZnAl Shape Memory Alloy Produced by Accumulative Roll Bonding and Subsequent Heat Treatment

In the present study, Cu/Zn/Al multi-layered composite was processed by accumulative roll bonding (ARB) through nine passes. Afterwards, heat treatment processes at various temperatures (750-950℃) and times (10-25min) were done on the prepared composites to fabricate CuZnAl shape memory alloys. The microstructure (composites and alloy) were investigated using scanning electron microscopy and X-ray diffraction. Tensile properties and shape memory effect of the composites and alloys were also investigated by tensile test. The microstructure investigations show that plastic instability and shear bands occurred in different layers in the composite. In addition, a composite with a uniform distribution of Zn and Al reinforcing layers was produced after nine passes. The tensile strength of the composite increased from the first cycle to the third ARB cycle and then decreased from the fifth to the ninth ARB cycle. Finally, the best UTS (about 330MPa) and elongation (about 31.52%) values were obtained on the third and first pass, respectively. The results showed that CuZnAl shape memory alloy was successfully fabricated by the accumulative roll bonding process and next heat treatment. It was also found that the alloys treated at 900°C and cooled in ice water consist of martensitic phase. Additionally, the alloy annealed at 900°C for 15 minutes exhibited a good shape memory effect and strength (about 503MPa).