微量掺杂氧化钇对热压烧结碳化硼的影响

Effect of micro-doping yttrium oxide on hot-press sintering of boron carbide

以B_(4)C和纳米级Y_(2)O_(3)为原料,通过热压烧结(HP)制备了致密B_(4)C-Y_(2)O_(3)复合材料,研究微量掺杂Y_(2)O_(3)和烧结温度对B_(4)C复合材料组织及性能的影响,并讨论了碳化硼晶粒生长机理和强韧化机制。结果表明,氧化钇可有效促进碳化硼的烧结,且B_(4)C-1 wt%Y_(2)O_(3)复合材料(烧结温度:2000℃;压力:30 MPa;烧结时间:1 min)性能最佳,其相对密度高达99.6%,弯曲强度为588 MPa,断裂韧性为5.0 MPa·m1/2,与纯碳化硼相比有较大的提升。在B_(4)C-Y_(2)O_(3)复合材料中发现了孪晶和粗大晶等晶粒异常生长的情况,碳化硼的晶粒生长受氧化钇与碳化硼晶界间复杂相互作用的影响。B_(4)C复合材料沿晶断裂和晶间断裂共存,其增韧机理遵循自增韧和孪晶增韧。

Dense B_(4)C composites were fabricated by hot-press sintering using B_(4)C and nano-scale yttrium oxide as the raw materials.The effects of Y_(2)O_(3) content and sintering temperature on the microstructure and mechanical properties of B_(4)C composites were studied.And the grain growth mechanism and the strengthening and toughening mechanism were discussed.B_(4)C-1 wt%Y_(2)O_(3) composites(sintering temperature:2000℃,pressure:30 MPa,dwell time:1 min)have the best properties,with the relative density of 99.6%,bending strength of 588 MPa and fracture toughness of 5.0 MPa·m1/2.Abnormal grain growth was found in B_(4)C-Y_(2)O_(3) composites,including twins and coarse grains.The grain growth is affected by the complex interaction of yttrium oxide and the grain boundary of boron carbide.The toughening mechanism of B_(4)C composites follows self-toughening and twinning-toughening,and the transgranular fracture and intergranular fracture coexist.