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Microstructure and hardness of Cu-Al-Mn-Ni SMA ingot before and after heat treatment

In this work the effect of heat treatment on microstructure and hardness of Cu-Al-Mn-Ni shape memory alloy was determined. Ingots (8 mm in diameter and 15 mm in length) were produced by melting and casting process. Melting was performed using the heat produced by electric arc and by a water-cooled, specially constructed copper anode that also served as a casting mould. The samples were analysed in as- cast state and in as-quenched state (900 °C/15 min/H2O). Microstructural analysis was performed by optical microscopy (OM), scanning electron microscopy (SEM) equipped by device for energy dispersive spectroscopy (EDS) and using differential scanning calorimeter (DSC). Preliminary metallographic analysis of investigated ingot confirmed that microstructure was consisted from martensite in both, as-cast and as-quenched state. A microhardness measurement was performed by Vickers method. Microhardness of Cu-Al-Ni-Mn shape memory alloy ingot was 260.8 HV10, and after heat treatment 285.6 HV10. By DSC analysis the phase transformation temperatures (As, Af, Ms and Mf) were determined.

Cu-Al-Mn-Ni, shape memory alloy, microstructure, hardness, heat treatment

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