Microstructure and wear properties of laser melted CoMoSi /Co₂Si metal suicide alloys

CoMoSi reinforced Co₂Si metal suicide alloys were fabricated by the laser melting process using Co-Mo-Si elemental powder blends as the precursor materials. Microstructure of the alloys was characterized by optical microscopy, scanning electron microscopy, X-ray diffraction and energy dispersive spectrometry. Wear resistance of the alloys was evaluated under dry sliding wear test conditions at room temperature. The metal silicide alloy consisting of predominantly the Co₂Si primary dendrite has the lowest wear resistance because of the serious cracking and spalling phenomena during sliding wear. Increasing the Mo content leads to the production of CoMoSi-reinforced-Co₂Si dual-phase structure and noticeable enhancement of wear resistance for the Co-Mo-Si metal silicide alloys. Although a CoMoSi/Co₂Si alloy with higher volume fraction of the ternary metal silicide CoMoSi has higher wear resistance, brittle fracturing and spalling are still the dominant wear mechanisms.