High Temperature Mechanical Properties and Microstructures of Thermally Stabilized Fe-Based Alloys Synthesized by Mechanical Alloying Followed by Hot Extrusion

The key requirement to consolidate high-energy mechanically alloyed nanocrystalline powders is to achieve densification and particle bonding without impairment in the mechanical properties. Recent demonstrations of consolidation methods involving high shear, pressure and temperature have shown promising results for bonding high strength particulate materials produced by mechanical alloying. In this study, we report the ability of multi-pass high temperature equal channel angular extrusion to produce bulk ferritic alloys from nanocrystalline Fe–Ni–Zr powders. Subsequent microstructural characterizations indicate limited grain growth as the average grain sizes remain smaller than 100 nm after processing temperatures of 600 °C and 700 °C, above which grains reach micron sizes. The compression test results reveal that the alloys exhibit high mechanical strength at room and moderately high temperatures compared to the pure Fe and Fe–Ni alloys without Zr addition.