(华中科技大学 材料成形及模具技术国家重点实验室，武汉 430074)
摘 要: 采用高能球磨法制备金属Ti粉负载纳米TiC颗粒复合细化剂(TiC/Ti细化剂)，研究细化剂加入量对铸态Al-Zn-Mg-Cu合金组织和性能的影响。结果表明：随着TiC/Ti细化剂加入量的增加，Al-Zn-Mg-Cu合金的晶粒尺寸逐渐减小；当加入量为0.5%(质量分数)时，晶粒形态由未添加细化剂时的525 μm树枝晶转变为119.7 μm的细等轴晶；随着细化剂加入量的增加，合金的晶粒尺寸逐渐粗化。铸态Al-Zn-Mg-Cu合金的第二相由T(AlZnMgCu)相和θ(Al2Cu)相组成，晶粒细化使第二相细化、分散，但细化剂的添加并不改变第二相的组成。随着细化剂加入量的增加，合金的抗拉强度和维氏硬度升高；当细化剂加入量为0.5%时，合金的抗拉强度和硬度分别为249.5 MPa和137.3 HV，较未添加时的分别提高32.9%和16.4%。
关键字: Al-Zn-Mg-Cu合金；纳米TiC/Ti细化剂；加入量；晶粒尺寸；抗拉强度；维氏硬度
（State Key Laboratory of Material Processing and Die and Mould Technology, Huazhong University of Science and Technology, Wuhan 430074, China）
Abstract:A novel kind of Ti supporting nano-sized TiC particles grain refiner (TiC/Ti refiner) was prepared by high-energy ball milling. The effect of refiner addition amount on the microstructure and mechanical properties of as-cast Al-Zn-Mg-Cu alloy was investigated. The results show that with the increase addition of TiC/Ti refiner, the average grain size of alloy decreases gradually. When the addition amount is 0.5% (mass fraction), the α(Al) grains transform from dendrites with average size of 525 μm to equiaxed grains with average size of 119.7 μm. The secondary phases of as-cast Al-Zn-Mg-Cu alloy consisted of T(AlZnMgCu) and θ(Al2Cu). The refining of α(Al) grain results in fine and uniformly distributed secondary phases, while the composition has not been changed. The tensile strength and hardness increase with the TiC/Ti refiner content; when the addition amount reaches to 0.5%, the optimized mechanical properties of the refined alloy is obtained with a tensile strength of 249.5 MPa and hardness of 137.3 HV. Compared to the unrefined alloy, the tensile strength and hardness are improved by 32.9% and 16.4%, respectively.
Key words: Al-Zn-Mg-Cu alloy; nano TiC/Ti refiner; addition amount; grain size; tensile strength; hardness
