Effect of Sc microalloying on microstructure evolution and mechanical properties of extruded Al–Zn–Mg–Cu alloys
Effect of Sc microalloying on microstructure evolution and mechanical properties of extruded Al–Zn–Mg–Cu alloys
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DOI：
10.1016/j.msea.2021.142197
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发表时间：
2021-10
期刊：
影响因子：
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通讯作者：
T. Ying;Guan Lidong;Tang Xiaoyi;Jingya Wang;Xiaoqin Zeng
中科院分区：
文献类型：
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作者：
T. Ying;Guan Lidong;Tang Xiaoyi;Jingya Wang;Xiaoqin Zeng
通过X射线衍射、光学显微镜、扫描电镜、电子背散射衍射、透射电镜等表征手段和拉伸试验，研究了微量Sc对Al-Zn-Mg-Cu合金显微组织和力学性能的影响。Sc的存在导致初生Al 3Sc相的形成，并表现出显着的改性效果的铸造显微组织与等轴显微组织中获得的含Sc合金，而不是在Sc合金的枝晶。在随后的热挤压过程中，由于纳米Al 3Sc弥散相对含Sc合金中位错运动和晶界迁移的钉扎作用，合金的晶粒得到明显细化，再结晶受到阻碍。Sc的加入显著提高了合金的力学性能，在350 °C挤压时，合金的屈服强度和抗拉强度分别为373.7 ± 3 MPa和490.3 ± 5 MPa，具有上级综合力学性能。Sc对挤压态合金的强化作用主要是由于Al_3Sc颗粒的细化和弥散强化。晶粒细化和弥散强化对屈服强度提高的贡献分别为：350 °C挤压获得的最高颗粒密度使含钪合金具有优异的力学性能。
The effect of microalloying Sc on the microstructure and mechanical properties of Al–Zn–Mg–Cu alloys was experimentally investigated through X-ray diffraction, optical microscopy, scanning electron microscopy, electron backscatter diffraction, and transmission electron microscopy characterizations and tensile tests. The presence of Sc caused the formation of the primary Al3Sc phase and behaved a significant modifying effect on the cast microstructure with an equiaxed microstructure attained in the Sc-bearing alloys rather than the dendrites in Sc-free alloys. In the subsequent thermal extrusion processing, a remarkable grain refinement and retardation of recrystallization occurred, because the nano-sized Al3Sc dispersoids contributed to the pinning effect on the dislocation movement and grain boundary migration in the Sc-bearing alloys. The mechanical properties were significantly improved with the addition of Sc. The superior comprehensive mechanical properties in the Sc-bearing alloys were achieved via the optimal extrusion at 350 °C with the yield strength and ultimate tensile strength of 373.7 ± 3 MPa and 490.3 ± 5 MPa, respectively. The strong strengthening behavior of the Sc addition in the extruded alloys is mainly attributed to the grain refinement and the dispersoid strengthening from the Al3Sc particles. The corresponding contributions to the increase in yield strength derived from the grain refinement and the dispersoid strengthening were estimated, which indicated that the highest particle density attained by extrusion at 350 °C resulted in the excellent mechanical properties of the Sc-bearing alloys.