Fe-B composite powder was produced by spray-dry of elemental iron and boron powders. Fe-ZrB₂ composite powder was made by the 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 supersaturated with boron due to the high cooling rate of molten particles on a substrate. Heat treatment of deposits 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 deposits decreases. The as-sprayed deposits produced using the Fe-ZrB₂ composite powder were composed of α, Fe₂B and Fe₃Zr. Heat treatment of the deposits at 1073 K results in the formation of FeB. The hardness of the deposit drops after heat treatment at 1073 K.