热压制备Mo-Nb-Si系新型高温金属硅化物合金

Preparation of Mo-Nb-Si system high-temperature metal silicides by hot-pressing sintering process

以Mo粉、Nb粉和S i粉为原料,采用机械活化/热压工艺制备(Mo1-xNbx)5Si3(x=0,0.4,0.6,1.0)型高温金属硅化物。通过XRD、SEM和EDS等分析手段对合金试样进行物相分析、显微组织观察、微区成分分析及力学性能测试。结果表明:合金试样的主要物相为Mo5Si3、α-Nb5Si3、γ-Nb5S i3及其(Mo,Nb)5Si3和β-(Nb,Mo)5Si3固溶体相,Mo有助于高温相β-Nb5S i3的相稳定;随着Nb含量的增加,硬度值呈上升趋势,合金硬度较高,达1 311.5～1 397.5HV;试样的压痕断裂韧度和抗压强度呈先增加后降低的趋势,当x=0.6时断裂韧度和抗压强度达到最大,分别为4.71MPa·m1/2和1 637MPa,Nb5Si3和Nbss(Nb基固溶体)有助于合金断裂韧度的提高。

High-temperature metal silicide（Mo1-xNbx）5Si3,（x=0,0.4,0.6,1.0） was synthesized from element Mo,Nb and Si powders by mechanical milling activation and hot-pressing sintering technology.The phase composition,microstructure,micro-area component analysis and mechanical properties were investigated by XRD,SEM and EDS etc.Results show that the main phases of these alloys are Mo5Si3,α-Nb5Si3,γ-Nb5Si3 and the solid solution phase of（Mo,Nb）5Si3 and β-（Nb,Mo）5Si3.β-Nb5Si3 is stabilized by adding Mo.With the content of Nb increasing,the hardness of the alloys increase to 1 311.5-1 397.5 HV,the indentation fracture toughness and compressive strength at first increase then decrease,when x=0.6,the maximum indentation fracture toughness and compressive strength is 4.71 MPa·m1/2 and 1 637 MPa respectively.Nb5Si3 and Nbss contribute to the improvement of fracture toughness of alloys.