New approach to amorphization of alloys with low glass forming ability via selective laser melting

Abstract

The paper presents a new approach to selective laser melting (SLM) of alloys with low glass-forming ability and the basics of microstructure evolution during SLM of iron-based metallic glasses. After extensive parameters optimization, a novel scanning strategy, involving two-step melting, comprising preliminary laser melting, followed by short-pulse amorphization, has been introduced to maximize the glassy phase fraction and ensure good magnetic properties. Single melted samples show poor amorphization with well separated amorphous regions and coercivity of 1032 A/m. Second melting increased the glassy phase content by over an order of magnitude - up to 89.6% and reduced coercive force over four-times to 238 A/m. X-ray diffractions show significant difference between, arising from melt, disordered Fe(Si) phase and devitrified, ordered Fe3Si. Coexistence of those phases has been shown in heat affected zone by electron diffraction. Beneficial effect of the novel remelting strategy has been explained on the basis of restricted crystallization in heat-affected zone and reduction of sample overheating, by application of the Point-Random strategy.