In-situ synchrotron X-ray diffraction analysis of the elastic behaviour of martensite and H-phase in a NiTiHf high temperature shape memory alloy fabricated by laser powder bed fusion
Jiajia Shen, Zhi Zeng, Mohammadreza Nematollahi, Norbert Schell, Emad Maawad, R.N. Vasin, Keyvan Safaei, Behrang Poorganji, Mohammad Elahinia, J.P. Oliveira
Abstract
High temperature shape memory alloys of the Ni-Ti-Hf system are potential candidates for aerospace applications where powder bed additive manufacturing technologies are being increasingly used. In this work, a Ti-rich NiTiHf high temperature shape memory alloy powder was processed by laser powder bed fusion. The standard heat treatment of 550 ⁰C for 3 hours was imposed to promote H-phase precipitation. At room temperature, the material has a dual-phase microstructure composed of martensite, the matrix, and H-phase, as a strengthening precipitate. High energy synchrotron X-ray diffraction is used to evaluate, in-situ, the elastic behaviour of the fabricated part. The deformation anisotropy of several (h k l) families of planes of both phases is evidenced. No major texture changes were observed upon macroscopic elastic loading. We illustrate the potential of using high energy synchrotron X-ray diffraction for detailed analyses of minority phases in additively manufactured components.