真空退火对原位Al2O3/Fe-Cr-Ni增强复合材料性能的影响

铁铬镍合金具有良好的高温强韧性和抗蠕变性,被广泛应用于制造航空发动机、工业燃气轮机等设备。利用原位合成和热压烧结工艺制备Al2O3/Fe-Cr-Ni复合材料。为减少脆性相对复合材料性能的影响,将热压烧结试样在1000℃下真空保温2h后退火。采用XRD和SEM等测试方法,研究热处理后Al2O3/Fe-Cr-Ni复合材料的微观结构和常温力学性能。结果表明:Al2O3/Fe-Cr-Ni复合材料主要由Fe-Cr-Ni合金相、Fe-Cr相和Al2O3陶瓷增强相组成。热压烧结试样的维氏硬度、抗弯强度和断裂韧度分别为4.16GPa、298.31MPa和8.04MPa·m1/2。经1000℃高温热处理后,复合材料中Fe-Cr相发生奥氏体转变和合金基体晶粒长大,导致硬度下降至2.98GPa。Fe-Cr-Ni合金基体中韧性相含量和基体连续性增加,使该复合材料的抗弯强度和断裂韧度明显上升,其值分别为459.33MPa和12.81MPa·m1/2。

Effect of vacuum annealing on performances of in-situ Al2 O3 reinforced Fe-Cr-Ni composites

Fe-Cr-Ni alloys were widely applied to produce aero-engine, industrial gas turbine and other equipments because of their high temperature strength and toughness and creep resistance. In-situ Al2O3/Fe-Cr-Ni composites were prepared by hot pressing sintering process and in-situ synthesis method. In order to reduce the effect of brittle phase on the properties of composites, the prepared samples were kept in vacuum for 2 h at 1000 ℃. Effect of heat treatment on microstructures and mechanical properties of Al2O3/Fe-Cr-Ni composites at room temperature was investigated by XRD and SEM. The results show that Al2O3/Fe-Cr-Ni composites are mainly composed of Fe-Cr-Ni alloy phase, Fe-Cr phase and Al2O3 ceramic reinforcement phase. The Vickers hardness, bending strength and fracture toughness of the hot pressed sintered samples are 4.16 GPa, 298.31 MPa and 8.04 MPa·m1/2, respectively. Austenitic transformation of Fe-Cr phase in composites results in the reduction of hardness to 2.98 GPa through high-heat treatment at 1000 ℃. The values of bending strength and fracture toughness increase obviously with the increasing of the ductile phase contents in the alloy matrix, which are 459.33 MPa and 12.81 MPa·m1/2, respectively.