激光熔化沉积TiC/GH5188复合材料的微观组织及拉伸性能OA

To improve the high-temperature performance of GH5188 cobalt-based superalloy,10％(volume fraction)TiC particle-reinforced GH5188 composites are fabricated by laser melting deposition(LMD).The microstructure and tensile properties are investigated,and the interfacial forming mechanism and the cause of the high-temperature performance degradation are discussed.The results show that the composite consists of TiC,(W,Ti)C1-x,and the austenitic γ phase.The submicron-thick(W,Ti)C1-x interfacial layer forms between the TiC particles and the matrix.The interfacial layer originates from the partial dissolution of TiC and the diffusion and substitution of W elements during the laser melting deposition process.At room temperature,the ultimate tensile strength(UTS)of the composite reaches 1198.9 MPa,which is 24.3％higher than that of the matrix alloy(964.3 MPa).However,at 1000 ℃,the UTS of the composite is 128.7 MPa,which is lower than the 162.5 MPa of the matrix alloy,with a decrease of 20.8％.The degradation in high-temperature strength is mainly due to the consumption of W elements in the matrix by the(W,Ti)C1-x interfacial layer,resulting in decrease in its mass fraction and weakening the solid-solution strengthening and dislocation-pinning effects on the matrix.