納米TiC/Ti細(xì)化劑加入量對鑄態(tài)Al-Zn-Cu-Mg合金組織和性能的影響

納米TiC/Ti細(xì)化劑加入量對鑄態(tài)Al-Zn-Cu-Mg合金組織和性能的影響Effect of nano TiC/Ti refiner addition on microstructure and properties of as-cast Al-Zn-Mg-Cu alloy

采用高能球磨法制備金屬Ti粉負(fù)載納米TiC顆粒復(fù)合細(xì)化劑(TiC/Ti細(xì)化劑)，研究細(xì)化劑加入量對鑄態(tài)Al-Zn-Mg-Cu合金組織和性能的影響。結(jié)果表明：隨著TiC/Ti細(xì)化劑加入量的增加，Al-Zn-Mg-Cu合金的晶粒尺寸逐漸減小；當(dāng)加入量為0.5%(質(zhì)量分?jǐn)?shù))時，晶粒形態(tài)由未添加細(xì)化劑時的525 μm樹枝晶轉(zhuǎn)變?yōu)?19.7 μm的細(xì)等軸晶；隨著細(xì)化劑加入量的增加，合金的晶粒尺寸逐漸粗化。鑄態(tài)Al-Zn-Mg-Cu合金的第二相由T(AlZnMgCu)相和θ(Al2Cu)相組成，晶粒細(xì)化使第二相細(xì)化、分散，但細(xì)化劑的添加并不改變第二相的組成。隨著細(xì)化劑加入量的增加，合金的抗拉強(qiáng)度和維氏硬度升高；當(dāng)細(xì)化劑加入量為0.5%時，合金的抗拉強(qiáng)度和硬度分別為249.5 MPa和137.3 HV，較未添加時的分別提高32.9%和16.4%。

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.

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