Production of Rapidly Solidified Iron Matrix Composite Deposits with Dispersed Boride Particles by Plasma Spraying

Fe-B composite powder was produced by spray-drying of elemental iron and boron powders. Fe-ZrB₂ composite powder was made by ball-milling of elemental iron and ZrB₂ powders. These powders were plasma-sprayed in low-pressure argon atmosphere to produce iron matrix composite deposits with dispersed boride particles. As-sprayed deposits formed using Fe-B composite powder are composed of ferrite (α) and austenite (γ) phase that is supersaturated with boron due to the high cooling rate of molten particles on a substrate. Heat treatment of the deposit at 673 K leads to the formation of Fe₃B. The deposit heat-treated at 1073 K is made up of α, Fe₂B, and FeB. With increasing heat-treatment temperature up to 1073 K, the hardness of the deposit decreases. As-sprayed deposit produced using Fe-ZrB₂ composite powder is composed of α, ZrB₂, Fe₂B, and Fe₃Zr. Heat treatment of the deposit at 1073 K results in the formation of FeB. Heat treatment at 1073 K lowers hardness of the deposit.