添加LaB_6对超细晶WC-Ni_3Al合金的组织与力学性能影响

Effect of LaB_6 addition on microstructure and mechanical properties of ultrafine grain WC-Ni_3Al alloys

通过球磨与低压烧结方法,制备超细晶WC-Ni3Al硬质合金。采用X线衍射、扫描电镜及力学性能测试方法,研究La B6掺杂对超细晶WC-Ni3Al合金的组织与力学性影响。研究结果表明:添加适量La B6可以提高烧结体的致密度和断裂韧性,减少WC颗粒的反常长大,抑制基体合金中的脱碳相Ni3W9C4的生成,但当加入过量的La B6后合金中出现另一种脱碳相Ni2W4C。在1 500℃烧结后,添加质量分数为0.096 7%La B6到WC-Ni3Al硬质合金中,合金的断裂韧性从13.1 MPa·m1/2提高到15.6 MPa·m1/2,而抗压缩强度达到3 500 MPa。

The ultrafine grain WC-Ni3 Al alloys with different La B6 contents were prepared by ball milling and low pressure sintering. Effects of La B6 doping on microstructure and mechanical properties of ultrafine grain WC-Ni3 Al alloys were investigated with X-ray diffraction, scanning electron microscope and mechanical properties testing. The results show that doping minor La B6 can increase the density and fracture toughness of the ultrafine grain WC-Ni3 Al alloys, and decrease the abnormal growth of WC grain. Meanwhile, the additions of La B6 decrease the volume fraction of Ni3W9C4 phase in ultrafine grain WC-Ni3 Al alloys. After low pressure sintering at 1 500 ℃, the fracture toughness increases from 15.6 MPa·m1/2 for alloy with free La B6 to 13.1 MPa·m1/2 for alloy with 0.097 6% La B6, and the comprehensive strength reaches 3 500 MPa.