搅拌摩擦加工工艺制备ZrO_2颗粒增强镁基复合材料的组织与力学性能

Microstructure and Mechanical Properties of ZrO_2 Particles Reinforced Magnesium-based Composites Preparated by Friction Stir Processing

利用4道次搅拌摩擦加工(FSP)工艺,分别将粒径为20nm的单斜晶ZrO_2(M-ZrO_2)颗粒和40nm的正方晶ZrO_2(T-ZrO_2)颗粒添加到AZ31镁合金中制备了ZrO_2颗粒增强镁基复合材料,研究了复合材料的显微组织与力学性能,并与无强化颗粒FSP镁合金的进行了对比。结果表明:M-ZrO_2颗粒和T-ZrO_2颗粒增强镁基复合材料的晶粒尺寸分别约为6μm和2μm;两种ZrO_2颗粒均弥散分布于复合材料中,且均未与基体反应生成新物相;ZrO_2颗粒可有效提高镁合金的硬度、屈服强度和抗拉强度,且T-ZrO_2颗粒的强化效果更好;无强化颗粒FSP镁合金与M-ZrO_2颗粒增强复合材料拉伸断口均具有混合断裂特征,前者的韧性断裂特征较明显,后者的脆性断裂特征较明显。

Four-pass friction stir processing （FSP） was applied to incorporate AZ31 magnesium alloy with 20 nm M-ZrO2 particle and 40 nm T-ZrO2 particle respectively, and thus ZrO2 particles reinforced magnesium-based composites were fabricated. Microstructure and mechanical properties of the composites were investigated, and compared with FSP sample without reinforced particle. Results show that the size of grains in stir zone of M-ZrO2 particle and T-ZrO2 particle reinforced magnesium-based composites was 6 μm and 2 μm, respectively. Both kinds of ZrO2 particles dispersed in stir zone and did not combine with matrix to form new phase. ZrO2 particles could increase microhardness, yield strength and tensile strength of the magnesium alloy, and T-ZrO2 particle had a better strengthening effect. The tensile fracture of the FSP sample without reinforced particle and with M ZrO2 particle both presented mixed fracture characteristics, and the former was incline to ductile fracture and the latter to brittle fracture.