Shock Consolidation of a Glass-Forming Crystalline Powder

Abstract

Plane shock waves were employed to consolidate a microcrystalline Markomet 1064 alloy powder (~50 μm particle size, Ni_(55.8)Mo_(25.7)_Cr_(9.7) B_(8.8)) with shock energies ranging from 210-595 kJ/kg. Metallurgical examination of the compacts reveals amorphous regions at particle junctions and interparticle boundaries which formed from shock melted material. A fine microcrystalline region was observed near the center of the larger amorphous regions. The volume fraction of the melt (amorphous + fine microcrystalline regions) increases from 0.006 to 0.28 over the energy range employed. The maximum metallic glass fraction retained was approximately 20% at energies near the maximum employed. The thermal history of spherical particles flux during the shock rise time was calculated. melt fraction, assuming all of the shock energy subject to constant energy The numerically predicted was input at the particle surface, is large than the experimentally measured melt fraction at low energies. TEM observations on the consolidated powder indicate extensive slip and deformation by twinning. The present melt fraction measurements indicate that while the shock energy is preferentially deposited near particle surfaces, a significant fraction of shock energy is also dissipated in plastic deformation of particle interiors.