Dense CoAl-Based Alloys with Improved Ductility: Solid-State Synthesis and Microstructure Control

摘要: Dense single- and multiphase B2 CoAl-based intermetallics were synthesized from fine elemental Co-Al blends by a completely solid-state processing route at temperatures as low 800 °C. To ensure full density of the final product, moderately high external pressure (≤500 MPa) was applied during reactive synthesis. Microstructure mechanical properties materials obtained investigated employing X-ray diffraction (XRD), scanning electron microscopy, transmission microhardness compression testing. improve room-temperature ductility, an attempt made to control microstructure hyperstoichiometric CoAl alloysvia solution treatment with subsequent aging. At early stages aging, Widmanstatten precipitates Co formed; coarsening dispersions long or higher temperature anneals resulted in pronounced compressive ductility overaged samples. In addition general precipitation, cellular precipitation observed alloys content. The relatively coarse equilibrium found rapidly overgrow metastable plates, causing rapid overaging these alloys. lattice parameter hyper-stoichiometric decrease linearly increasing