Effect of W content on compression and thermal fatigue behavior of WCp/steel matrix composites

WCp/steel surface composites were endowed with gradient structure and prepared by powder metallurgy. The mechanical properties, thermal fatigue properties and microstructure of the composites with different W content in the transition layers were analyzed by scanning electron microscopy, metallographic microscope, compression and thermal shock tests, and the influence of W addition on the composites performances was examined. The results show that the composition and structure between the composite layer and the substrate layer are varied by adding tungsten powder in the transition layer, the conflicts in stress, strain, and thermal expansion between the composite layer and the substrate layer are decreased. With the mass fraction of tungsten powder increasing, the W can diffuse both into the substrate layer and the composite layer, which leads to a new phase appearing in the transition layer. The bond between the substrate layer and the composite layer is reinforced. When the W content in the transition layer reaches 30% in mass fraction, the compressive strength reaches 553MPa, and thermal fatigue resistance of WCp/steel surface composite is improved.