albowaz91复合材料的挤压铸造制备工艺与力学性能word格式论文.docxVIP

摘要本文采用不同制备工艺(不同烧结时间、不同烧结温度、不同粘结剂种 类和含量 ) 制备了硼酸铝晶须预制块，并利用挤压铸造法成功的制备了 [AlBO]w/AZ91 复合材料，硼酸铝晶须体积分数均为 20%。利用金相显微镜 (OM)、扫描电镜(SEM)和透射电镜(TEM)对材料的显微组织和界面反应进行 了观察；讨论预制块制备工艺对预制块压缩强度的影响。利用拉伸性能考察 了预制块制备工艺和不同热处理工艺(T4 和 T6)对复合材料性能的影响规律 和机制。利用 XRD 对硼酸铝晶须预制块烧结态的观察表面，晶须表面产生 α- Al2O3相，在相同的烧结条件下，相对于无胶预制块而言，加入硅胶和磷酸 铝胶的预制块晶须表面产生的α-Al2O3相数量较少。研究结果表明复合材料中存在较多细小、不连续的界面反应物，经衍射 斑点标定为MgO。这些界面反应物主要来自挤压铸造时粘结剂和硼酸铝晶 须与熔融的镁反应。这些MgO与硼酸铝晶须之间存在一定的位向关系，结 合强度较高。所以，适量的界面反应有利于界面结合，改进复合材料的性 能。同时可以观察到，复合材料的时效析出产物为Mg17Al12，并且复合材料 的峰时效比基体合金提前到达。与基体合金相比，复合材料的力学性能(常温拉伸性能)有较大程度的提 高。含磷酸铝胶预制块制备的复合材料的弹性模量、屈服强度和抗拉强度优 于无胶预制块所制备的复合材料。其中用含磷酸铝胶 20ml，在 1450℃烧结 4.5 小时工艺下的预制块制备的[AlBO]w/AZ91 复合材料的抗拉强度最高。 并且与无胶预制块所制备的复合材料相比，含磷酸铝胶预制块制备的复合材 料中晶须预制块的变形较少，复合材料铸锭中不同部位的力学性能分布比无 胶预制块所制备的复合材料均匀。关键词硼酸铝晶须；预制块；镁基复合材料；界面；力学性能Abstract[AlBO]w/AZ91 magnesium matrix composites were fabricated by squeeze casting technique using preforms with different technique (different sinter time, different sinter temperature, different kinds of binders and different content of binders), the volume fraction of the aluminum borate whisker was 20% in all cases. The microstructures and interfacial reaction of the materials were examined by means of optical microscopy (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM). The effect of the fabrication of preform on the compressive strength were investigated by compressive test. The effect of the fabrication of preform and heat treatment on the properties of the composites were studied by the tensile test.The results showed that, there exists α-Al2O3 on the surface of the aluminum borate whisker after sintering. Less α-Al2O3 existed on the surface of the aluminum borate whisker with silica binder and acid phosphate binder than that of those without binder.The results showed that, a lot of fine discrete interfacial reaction products were observed at the [AlBO]w-AZ91 interface, and the interfacial reaction product is MgO confirmed by the ring diffraction pattern. These interfaci