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以高能球磨机械合金化制得的WC-40%Al2O3复合粉末为原料,采用二步热压烧结法制备复合块体。首先将粉末坯体在压力条件下加热到较高的温度T1,获得相对致密的坯体结构,此时存在临界的可收缩气孔,然后将其保温在一个相对较低的温度T2,通过低温保温实现致密化。由于烧结过程温度相对较低,晶粒长大被有效抑制。采用XRD、SEM、扫描探针(SPM)对复合材料的物相、微观结构进行表征,并进行正交实验分析第二步烧结温度以及保温时间对复合块体微观组织和力学性能影响。结果表明:当T1=1600℃、T2=1450℃保温6h时,WC-40%Al2O3复合材料成形致密度达到99.03%,维氏硬度和断裂韧性分别为18.36 GPa和10.4MPa·m1/2,抗弯强度为1162.1MPa.
WC-40% Al2O3 composite powder obtained by high-energy ball milling mechanical alloying was used as raw material, and two-step hot-pressing sintering method was used to prepare composite block. First, the powder body is heated to a higher temperature T1 under a pressure condition to obtain a relatively compact structure of the body, at which time there exists a critical shrinkable porosity, which is then insulated at a relatively low temperature T2, To achieve densification. As the sintering temperature is relatively low, grain growth is effectively suppressed. The phase and microstructure of the composites were characterized by XRD, SEM and SPM. The effects of the second sintering temperature and holding time on the microstructure and mechanical properties of the composites were characterized by orthogonal experiments. The results show that the forming density of WC-40% Al2O3 composites reaches 99.03% when Vickers hardness is T1 = 1600 ℃ and T2 = 1450 ℃, and the Vickers hardness and fracture toughness are 18.36 GPa and 10.4MPa · m1 / 2, respectively Bending strength of 1162.1MPa.