ULTRAFINE GRAINED Cu-Al-Mn SHAPE MEMORY ALLOY PROCESSED BY SEVERE PLASTIC DEFORMATION IN TWO PHASE REGION

Severe plastic deformation processing is a novel technique, for the production of nano/ultrafine grain structures in metallic material. The grain size could be significantly decreased by this process because of ultra-high strains, which induced in material. This work aims to investigate the possibility of grain refinement of Cu-Al-Mn shape memory alloy (SMA) sheet by accumulative roll bonding (ARB) to nanometer. The effect of ARB at 600 °C on the microstructure and texture evolution of Cu-Al-Mn SMA was investigated using optical microscopy, X-ray diffraction (XRD) and scanning electronmicroscopy. The initial microstructure of as-quenched alloy showed zig-zag morphology of b1¢ martensite with grain size of about 600-800 mm. The amount of grain refinement increased with increasing the ARB pass number. XRD and SEM investigations showed that after 5 passes of theprocess, initial coarse grains and martensite phases were completely disappeared and a fine microstructure of a + b with grain size of about 100 nm was dominated.

کلیدواژه ها:

Cu-based shape memory alloys ، Accumulative roll bonding ، Martensite ، Microstructure