Laser Surface Alloying of Titanium with Silicon

Abstract

An investigation is reported of the laser surface alloying of titanium with silicon using a 2 kW carbon dioxide laser and continuous feed of silicon powder. Alloyed zones containing up to 20 at.-%Si were produced using the following processing parameters: 1·8 kW laser power, 2 mm beam diameter, 7mm S^-l traverse speed, and powder feed rates ranging from 0·053 to 0·071 g S^-1. Fine scale microstructures were produced by solidification sequences involving primary titanium dendrites or primary Ti₅Si₃, and β + Ti₅Si₃ eutectic. In the solid state, martensite formation and precipitation of Ti₅Si₃ occurred. The hardness increased with silicon content up to 620 HV at 20 at.-%Si.