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采用湿成型法成功制备了比重差别大的WO3颗粒(WO3p)和硼酸铝晶须(ABOw)混杂预制块,用挤压铸造法制备混杂铝基复合材料。混杂复合材料中含(原子分数)5%WO3p和20%ABOw,不同大小的WO3p尺寸分别为18和3μm。采用扫描电镜(SEM)和万能拉伸试验机对制备的混杂复合材料试样进行微观组织观察和拉伸性能测试。复合材料组织观察表明,WO3p和ABOw在基体中随机、均匀地分布,在高倍照片中可以观察到大尺寸WO3p存在裂纹,铝液不能渗入到裂纹中。力学性能研究结果表明,尺寸较小的颗粒增强的复合材料具有高的抗拉强度和断裂延伸率;含大尺寸WO3p的混杂复合材料的抗拉强度、屈服强度和断裂延伸率分别为266.8,197.3 MPa和1.16%,含小尺寸WO3p的混杂复合材料的抗拉强度、屈服强度和延伸率分别为290.3,180.5 MPa和1.37%。复合材料拉伸断口形貌观察表明,两种不同WO3p尺寸的混杂复合材料断裂机制有所不同,大颗粒增强复合材料中大颗粒发生断裂,裂纹穿过颗粒扩展,晶须与界面脱粘;小颗粒增强复合材料中小颗粒与基体界面脱粘以及晶须与界面脱粘,但晶须脱粘数量明显减少,晶须拔出数量增多。
WO3powder and ABOw mixed preform were successfully prepared by wet-forming method and mixed aluminum matrix composites were prepared by extrusion casting. The hybrid composites contained (atomic fraction) 5% WO3p and 20% ABOw, and WO3p sizes of different sizes were 18 and 3 μm, respectively. The hybrid composite samples prepared by scanning electron microscopy (SEM) and universal tensile testing machine were tested microstructurally and tensile properties. The results of composite microstructure observation showed that the WO3p and ABOw were randomly and uniformly distributed in the matrix, and the cracks of large size WO3p could be observed in high magnification photographs, and the molten aluminum could not penetrate into the cracks. The mechanical properties of the composites show that the composites with smaller particle size have higher tensile strength and elongation at break. The tensile strength, yield strength and elongation at break of hybrid composites with large size WO3p are 266.8 and 197.3 The tensile strength, yield strength and elongation of the hybrid composites with MPa and 1.16% and WO3p with small size were 290.3,180.5 MPa and 1.37%, respectively. The tensile fracture morphology of the composites shows that the fracture mechanism of the hybrid composites with two different WO3p sizes is different. The large particles in the large particle reinforced composites are broken, the crack propagates through the particles and the whiskers debond with the interface. Particle reinforced composite materials, small particles and the matrix interface debonding and debonding the whisker and the interface, but significantly reduced the number of whiskers debonding, increasing the number of whiskers to pull out.