Precision processing of Nb-Si alloy via water-jet guided laser: Realization of inhibited-oxidation and small-taper

Abstract

Nb-Si alloy holds great promise as a crucial high-temperature material for aero-engine hot end components. Nevertheless, its hardness and relatively low room temperature fracture toughness as well as high temperature oxidation resistance becomes an obstacle for precise processing. The water-jet guided laser (WJGL) technology was introduced to process Nb-Si alloys with high precision and minimized heat-affected zone. Notably, in contrast to nanosecond conventional laser processing, under the conditions of a 20 W laser power and a cutting speed of 5 mm/s, WJGL can slice through an alloy specimen with a width of 10 mm and a thickness of 3 mm within 20 s, all while maintaining a stationary laser focus. The continuous flowing of the water jet sweeps away the laser-induced molten residues which helps to minimize thermal impact and reduce severe oxidation, leading to a thin re-melted layer with thickness of hundreds of nanometers on the processing surface. Therefore, a remarkable minimum surface roughness of 0.8 μm has been attained by WJGL, even more impressively, for a through-hole with a diameter of 1 mm and a depth of 3 mm, the taper was constrained to 0.0016°, which is hard to obtain through conventional processing. Our study conclusively demonstrates that WJGL technology represents a viable and efficient alternative for the processing of Nb-Si alloys.