Hot direct extrusion—A novel method to produce abrasion-resistant metal-matrix composites

This paper discusses hot direct extrusion as a novel method to produce rods made of a metal-matrix composite (MMC). Due to the excellent abrasive wear resistance of hard phase and iron-base metal powder blends, hot direct extrusion is a highly promising method of producing long cylindrical products. This production process combines sintering of the capsuled powder mixtures at high temperatures and subsequent pressing of the capsules through an extrusion die to produce an (almost) completely densified MMC. The simpler capsule technique is less expensive than HIP cladding, which is a standard method of producing components and tools with thick, wear-resistant PM-layers. The extruded MMC were investigated with respect to their microstructure and abrasive wear resistance. Cross-sections show an alignment of the added hard phases, and pin-on-disc tests of heat-treated MMC clarified the effect of the added hard phase on the wear resistance.