M. Koyama, M. Murakami, Shibaura Institute of Technology, Tokyo, Japan; T. Sawaguchi, K. Ogawa, T. Kikuchi, National Institute for Materials Science, Tsukuba, Japan
We have recently reported that the ductility of Fe-Mn-Si shape memory alloys can be greatly improved by replacing a part of Si with a small amount of Al without decaying the shape memory effect. Enhancement of the ductility is ascribed to the introduction of deformation twins in addition to stress-induced hcp martensite on loading. In this work, the shape recovery strains and recovery temperatures were measured for Fe-30-5Si-1Al alloy and corrosion-resistant Fe-28Mn-5Si-1Al-5Cr alloy. The maximum shape recovery strain of Al-added alloys exceeded 2%, which was comparable to those of the alloys without Al addition. The initial tensile strain required for obtaining the maximum shape recovery strain was about 8% in Al-added alloys, which was about twice larger than that of non-Al alloys, probably due to the intrusion of deformation twins. It was also found that the shape recovery finishing temperature was as low as about 470K.
Summary: We investigated the shape memory property on Fe-Mn-Si-Al and Fe-Mn-Si-Al-Cr. And we concluded as following.
1) Maximum recovery strain is about 2% with 8% initial strain without training.
2) shape recovery starts at about 60 degrees C and finishes at about 220 degrees C.
3) Fe-Mn-Si-Al and Fe-Mn-Si-Al-Cr have similar shape memory and mechanical properties.
