Al-TiO_2-C系热扩散反应合成铝基复合材料的组织与性能

The Mechanical Properties of the Composites Fabricated by Exothermic Dispersition Reaction for Al-TiO_2-C System

讨论了Al-TiO2-C系热扩散反应合成铝基复合材料的组织、常温力学性能及其断裂机理。结果表明:当碳、TiO2化学计量比为0时,增强相由α-Al2O3和Al3Ti组成;随碳、TiO2化学计量比的增加,碳与Al3Ti中的钛结合生成TiC,Al3Ti逐渐减少;在碳、TiO2化学计量比为1时, Al3Ti基本消失,此时室温下的抗拉强度和伸长率同步提高,分别由274 MPa和3．0％上升到351 MPa和6．0％;因Al3Ti与基体的结合强度高于自身断裂强度,拉伸时首先自身萌生裂纹,并扩展至基体引起断裂,并在Al3Ti四周形成较大韧窝,Al3Ti不利于强度的进一步提高。

The mechanical properties, reinforcement and fracture mechanism of the composites fabricated by in situ reaction method in the Al-TiO2-C system were studied. When the C/TiO2 mole ratio was zero, the reinforcements of the composites were composed of α-Al2O3 and Al3 Ti, the ultimate tensile strength and elongation were 274 MPa and 3. 0% respectively at morn temperature. The fracture mechanism of the composite was characterized by initiation firstly in Al3Ti rods and then propagation to the interface. When the C/TiO2 mole ratios increased, the amount of Al3Ti phase decreased, the ultimate tensile strength and elongation increased. When the C/TiO2 mole ratio reached 1, the Al3Ti phase was almost eliminated, the ultimate tensile strength and elongation were promoted to 351 MPa and 6. 0% respectively. There were big ductile dimples around the Al3Ti and fracture by themselves in the fracture surfaces of the composites. The fission first occurred in the Al3Ti and then diffused to the matrix. Therefore, the Al3Ti phase was not benefit to strengthening the composites.