Shape memory alloys: Unlocking the potential of an ultra-light biocompatible alloy


Cyclic heat treatment probes abnormal grain growth to enhance Mg–Sc superelasticity

Dr. Sutou (left) and Dr. Ando, who have conducted this research

The quest for the next shape memory alloys (SMAs) for transformative applications in aerospace and medicine requires a departure from conventional alloys based on heavy metals such as Ni, Fe, Co, and Cu. To this end, Mg–Sc alloys, with extremely low densities and inherent biocompatibility, promise to be the ideal candidates—provided that a mechanism conducive to shape memory can be demonstrated in Mg-based alloys.

In a recent article, an AIMR team led by Yuji Sutou and Daisuke Ando addressed this problem by focusing on the effects of abnormal grain growth on the superelasticity of polycrystalline Mg–Sc alloys1.

“Grain enlargement is a known approach to improving superelasticity in conventional Cu- and Fe-based SMAs,” says Sutou. “Here, we use cyclic heat treatment (CHT) to investigate the mechanism of the abnormal grain growth in Mg–Sc alloys—aiming to improve the alloys’ superelasticity.”

The analysis of each stage of the CHT revealed that a lower holding temperature, longer solution heat treatment time, and slower heating rates resulted in more effective grain growth, lager and more uniform grains, and sharper subgrains, respectively, improving Mg–Sc superelasticity.

“The understanding of how CHT controls Mg–Sc grain enlargement is an important step towards isolating the ultra-light biocompatible SMA,” explains Sutou. “It gave us the ability to use the composition and microstructure to control Mg–Sc properties such as high strength and larger elongation2—all relevant to the design of future SMAs and related materials.”

(Author: Patrick Han)


  1. Yamagishi K., Onyam K., Ogawa Y., Ando D. and Sutou Y. Abnormal grain growth through cyclic heat treatment in a Mg–Sc alloy Journal of Alloys and Compounds 938, 168415 (2023). | article
  2. Yamagishi K., Ogawa Y., Ando D. and Sutou Y. Adjustable room temperature deformation behavior of Mg–Sc alloy: From superelasticity to slip deformation via TRIP effect Journal of Alloys and Compounds 931, 167507 (2023). | article

This research highlight has been approved by the authors of the original article and all information and data contained within has been provided by said authors.