Al2O3/ TiB2/Al学性能复合材料的微观结构和高温力学性能

Microstructure and elevated temperature mechanical properties of Al2O3/ TiB2/Al composites

摘要:

以细雾化铝粉和TiB₂颗粒为原料,通过粉末冶金和热轧制制备微米TiB₂和纳米Al₂O₃颗粒增强铝基复合材料。室温时,由于TiB₂和Al₂O₃的综合强化作用,Al₂O₃/TiB₂/Al复合材料的屈服强度和抗拉强度分别为258.7MPa和279.3MPa,测试温度升至350℃时,TiB₂颗粒的增强效果显著减弱,原位纳米Al₂O₃颗粒与位错的交互作用使得复合材料的屈服强度和抗拉强度达到98.2MPa和122.5MPa。在350℃退火1000h后,由于纳米Al₂O₃对晶界的钉扎作用抑制晶粒长大,强度和硬度未发生显著的降低。随着测试温度上升,复合材料的主要断裂机制从TiB₂颗粒断裂向颗粒与基体的界面解离转变。

Abstract:

Aluminum matrix composites reinforced with micro-TiB₂ and nano-Al₂O₃ particles were successfully fabricated by combining powder metallurgy and hot rolling with raw materials of fine atomized aluminum powders and TiB₂ particles. The Al₂O₃/TiB₂/Al composites exhibited a yield strength of 258.7 MPa and an ultimate tensile strength of 279.3 MPa at 25 °C due to the comprehensive strengthening effect of TiB₂ and Al₂O₃ particles. The strengthening effect of TiB₂ particles was significantly weakened with temperature rising to 350 ℃, and the Orowan strengthening mechanism between nano-Al₂O₃ and dislocation made the yield strength and tensile strength of the composite material reach 98.2MPa and 122.5MPa. After annealing at 350 ℃ for 1000h, due to the pinning effect of nano-Al₂O₃ on grain boundaries, the grains growth were suppressed significantly and the strength and hardness did not decrease significantly. The main fracture mechanism of composites changed from brittle TiB₂ particle fracture to interface debonding between TiB₂ and the matrix from room temperature to elevated temperature.