Stress-induced martensitic transformations in NiTi and NiTi-TiC compositesinvestigated by neutron diffraction

Superelastic NiTi (51.0 at.% Ni) specimens reinforced with 0, 10 and 20 vol .% TiC particles were deformed under uniaxial compression while neutron dif fraction spectra were collected. The experiments yielded in-situ measuremen ts of the thermoelastic stress-induced transformation. The evolution of aus tenite/martensite phase fractions and of elastic strains in the reinforcing TiC particles and the austenite matrix were obtained by Rietveld refinemen t [1] during the loading cycle as the austenite transforms to martensite (a nd its subsequent back transformation during unloading). Phase fractions an d strains are discussed in terms of load transfer in composites where the m atrix undergoes a stress-induced phase transformation. (C) 1999 Elsevier Sc ience S.A. All rights reserved.