Strengthening and plastic flow of Ni3Al alloy microcrystals

Ni3Al alloys exhibit remarkable deformation characteristics at small scales that are tied to their unique dislocation core structures. The present work examines microcrystal strengthening and flow for a binary Ni3Al alloy and two alloys containing −0.25% Hf and −1.0% Ta, and evaluates their response relative to known dislocation mechanisms for this material and sample size effects in other materials. The work includes analysis of the flow-stress anomaly mechanisms, dislocation velocity, the single-arm source model, exhaustion strengthening and dislocation multiplication for describing the response of Ni3Al alloy microcrystals. Primary remaining needs are to understand the nature of double cross slip and dislocation sources that trigger the onset of flow and limit size-dependent strengthening.