Effect of nano-WC reinforcement on high temperature mechanical properties and fracture mechanism of GH3536 deposited by oscillating laser

Abstract

The GH3536 pure alloy and nano-WC/GH3536 composite material were fabricated using the circular oscillating laser deposition technique. Their microstructure, room temperature (25 °C) and high temperature (980 °C) tensile properties, as well as crack and fracture morphology, were comprehensively analyzed. The results showed that at 25 °C, compared with the pure alloy, the composite material exhibited a 17 % increase in yield strength, a 7 % decrease in fracture strength, and a 95 % reduction in fracture elongation. At 980 °C, the WC/GH3536 composite demonstrated a 9 % increase in yield strength, a 14 % increase in fracture strength, and a 46 % improvement in fracture elongation, compared to the pure alloy. Fracture morphology analysis revealed that with increasing temperature, the fracture mechanism of the pure alloy transitioned from ductile to brittle, while the WC/GH3536 composite toughness has improved. This change is attributed to different grain growth patterns in the pure alloy and WC/GH3536 composite at 980 °C. The pure alloy's microstructure, initially composed of fine and regular crystal cells, transformed into large grains with different orientations. The precipitation phase is discontinuous, leading to intergranular fracture. In contrast, the WC/GH3536 composite's microstructure, reinforced by the precipitation of additional W-rich carbides, strengthened the existing precipitate network, thus preventing intergranular fracture.