The influence of temperature on lattice parameters of coexisting phases in NiTi shape memory alloys - a neutron diffraction study
Materials Science and Engineering a-Structural Materials Properties Microstructure and Processing 378(1-2): 161-164
NiTi shape memory alloys were investigated by Rietveld refinement of neutron diffraction data at various temperatures. For an aged sample of nominal composition Ni50.7Ti49.3 at 294 K, 82 austenite, R-phase, and Ni4Ti3 precipitates coexist, and the Rietveld refinement provides accurate lattice parameters for the phases in this microstructure. The observed rhombohedral shape deformation occurring with the formation of Ni4Ti3 and R-phase in the 82 matrix is similar in magnitude and of opposite sign. Thus the strain field around a Ni4Ti3 precipitate can be compensated by a single variant of R-phase. (C) 2004 Elsevier B.V. All rights reserved.