Phase transformations in engineering materials

Phase transformations in engineering materials are inevitably related to mechanical behaviour and are often precursors to residual stress and distortion. Neutron scattering in general is a valuable tool for studying their effects, and pulsed neutrons are of special value, because of the inherently comprehensive crystallographic coverage they provide in each measurement. At the Manuel Lujan neutron scattering center several different research programs have addressed the relationships between phase transformation / mechanical behaviour and residual strains. Three disparate examples are presented; 1) Stress induced transformation in a NiTi shape memory alloy, 2) Cryogenically induced transformation in a quenched 5180 steel, and 3) Time resolved evolution of strain induced martensite in 304 stainless steel. In each case a brief description of the principal result will be discussed in the context of using neutrons for the measurement.