Solid-State Amorphization ofZr3Al: Evidence of an Elastic Instability and First-Order Phase Transformation

Changes in shear elastic constant, long-range order, and lattice parameter were measured during disordering and eventual amorphization of ${\mathrm{Zr}}_3$Al by ion irradiation. Large (≃50%) elastic softening was observed during disordering, and anomalies occurred in all three measured parameters over a narrow range of ion doses. The results indicate that a first-order phase transformation triggered by an elastic instability occurs during solid-state amorphization. The changes reported here during disordering and amorphization are very similar to behavior observed previously in a large number of solids during heating to melting.