MICROSTRUCTURES AND MECHANICAL PROPERTIES OF LAMINATED STRUCTURAL Nb-Ti-Al COMPOSITES FABRICATED BY LASER DEPOSITION

摘要

Based on design to match the strength and toughness, a laminated structural material made of brittle A15-Nb{sub}3Al alloy and ductile B2 NbTiAl alloy using laser deposition was developed. The A15/B2 laminated composites were prepared with different layer thickness ratios. The element compositions and microstructures show periodic variation in the laminated deposition layers and gradual change at the interface within two neighboring layers. Cracks in the brittle A15-Nb{sub}3Al alloy layers were effectively limited. The β/B2 phase alloys have much low microhardnesses than that of δ-Nb{sub}3Al based alloys. The microhardness distribution of the laminated composites shows periodic variation in the deposited layers and gradual change at the interface within two neighbouring layers. The compressive properties at 900°C and room temperature and the fracture toughness of the laminated composites with different layer thicknesses were studied. The results approve that the laminated composites have both high strength and good fracture toughness.