Diffraction strain measurements in a partially crystallized bulk metallic glass composite containing ductile particles

In situ diffraction experiments were performed with high-energy synchrotron X-rays to examine load partitioning and high-stress relaxation during uniaxial compression of a bulk metallic glass composite containing both ductile tantalum particles and crystallized matrix material. The tantalum particles yielded at an applied stress of −800 MPa, while the matrix precipitates remained elastic up to the maximum applied stress of −1250 MPa. The von Mises effective stress in the tantalum particles at yielding was 1500 MPa, well in excess of typical tantalum yield stresses, which is attributed to a combination of solid-solution strengthening and the inhibition of dislocation motion in the 1–2 μm particles. A series of constant crosshead-position measurements made at −1250 MPa suggested the possibility of room-temperature matrix relaxation under high applied loads.