Liquid phase sintering of iron-carbon alloys with boron additions

Iron-carbon-boron compositions can be sintered to high density but nevertheless exhibit poor mechanical properties. In the present study, an alloy series based on water atomised iron powder and elemental graphite and boron powder, with alloying elements nickel and molybdenum, was investigated. The carbide forming element molybdenum is used to protect boron from reaction with carbon. When the carbon content is smaller than 0.4%, the interaction between boron and carbon is not significant. At a higher carbon content, a balance is necessary between the carbide forming element and carbon. Mechanical properties are sensitive to the remnants of the eutectic liquid phase that forms brittle intergrain films. Optimisation of the boron, carbon, and molybdenum are important to increasing sintered density without sacrificing strength and ductility.