Microstructure and mechanical properties of nickel aluminide powders consolidated by extrusion and hot isostatic pressing.

摘要

The influence of alloying additions of iron and chromium, alone and in combination with molybdenum and zirconium, on the heat treatment response and mechanical properties of powder metallurgy Ni(sub 3)Al based materials consolidated by hot extrusion has been characterized in detail. Consolidation of the nickel aluminide powders by hot isostatic pressing (HIP) has been examined as an alternative to extrusion. Densification has been simulated using a model that describes consolidation by the additive effects of plastic flow, power-law creep, boundary diffusion, and Nabarro-Herring and Coble creep. The model has been used to develop maps that describe densification for any combination of time, temperature, and pressure. The best available material property data and parameters from experiments have been used to develop maps that describe HIP consolidation experiments with reasonable accuracy. Finite element models were developed as an extension of the HIP map approach to provide detailed simulations of particle deformation during densification. Preliminary results for both monosized and bimodal particle distributions indicate that this particle level approach is useful for simulating microstructural development resulting from different combinations of consolidation parameters. 45 refs., 22 figs., 22 figs., 4 tabs.