Understanding of microstructure and shape memory characteristics of SLM Ti-Nb alloys

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K03814
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 18020:Manufacturing and production engineering-related
• Research Institution: National Institute for Materials Science
• Principal Investigator: WATANABE MAKOTO 国立研究開発法人物質・材料研究機構, 構造材料研究センター, 副センター長 (00391219)
• Co-Investigator(Kenkyū-buntansha): 草野 正大 国立研究開発法人物質・材料研究機構, 構造材料研究センター, 主任研究員 (60822583)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: レーザ粉末床溶融結合法 / Ti-Nb / 三次元積層造形 / 形状記憶特性

Outline of Final Research Achievements

In this study, Ti-42wt.%Nb alloys were fabricated by laser powder bed fusion and the effects of process conditions and solution treatment on the microstructure and superelastic properties of the specimens were investigated. It was found that the amount of precipitates increased with increasing laser energy density, and that the precipitates consisted of α and α'' phases, which were also increased by solution treatment. Superelastic behaviour was also observed, although the superelastic recovery strain was less than that of the cast material, with a maximum of about 0.32%. The highest recovery strain was observed under laser conditions with low precipitation, suggesting the influence of precipitation. It was expected that the superelastic properties could be improved in the future by controlling the crystal orientation.

Free Research Field

三次元積層造形プロセス

Academic Significance and Societal Importance of the Research Achievements

レーザ積層造形（LPBF）プロセスの形状記憶合金への適用研究は、Ni-Tiに限られた状態となっているが、Ni-Tiは金属アレルギーの原因となるNiを含有することから、本研究ではNiを含まないTi-Nb系に着目し、その造形プロセスの最適化や超弾性特性について評価を行った。これまでに十分に調査されていない材料系に対して調査することで、新しい多くの知見を得ることができ、またLPBFならではの課題が明らかになった。LPBF法の利点を生かしつつ、安全かつ高性能な新しい形状記憶部材の開発につながるとともに、今後解明すべき学術的課題を明らかにすることが出来た。