Martensitic transformation and shape memory effect in Mn-rich Cu-Mn-Al alloys

Ito, Tatsuya ; Xu, S.*; Xu, X.*; Omori, Toshihiro*; Kainuma, Ryosuke*

The microstructure, crystal structures, cold workability, and martensitic transformation temperatures of several Cu $_{100-{it x}-{it y}}$ Mn $_{it x}$ Al $_{it y}$ (40 55; 10 13; at%) alloys were analyzed. For the first time, martensitic transformation was revealed Mn-rich Cu-Mn-Al alloys. The surface relief of the martensite phase reversibly appeared and disappeared during cooling and heating, along with small thermal hysteresis, implying a thermoelastic transformation. The crystal structures of the parent and martensite phases are B2 and 2M(BCT), respectively, with c $/a being approximately 1.35. Cold workability improves with decreasing Al content, exhibiting a trend similar to that observed for previously reported Cu-rich Cu-Al-Mn shape memory alloys. The martensitic transformation temperatures decrease with increasing Al content and increase with increasing Mn content. These results are consistent with the stability trends of the parent body-centered cubic phase in the phase diagram at high temperature. The shape memory effect with a recovery strain of 1.3% was observed in a 5.0% pre-stretched Cu$_{39}$$ Mn $_{50}$ Al $_{11}$ (at%) sample. This alloy demonstrates moderate cold workability and cost-effectiveness, exhibiting potential as an alternative for conventional shape memory alloys in various applications.

Language	:	English
Journal	:	Shape Memory and Superelasticity
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Pages	:	9 Pages
Publication Year/Month	:	2025/00
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Paper URL	:	https://doi.org/10.1007/s40830-025-00519-y
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Keywords	:	Mn-Cu-Al alloys; Martensitic Transformation; Crystal Structure; Shape Memory Effect
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Registration No. : AA20240510
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