Li Ying, He Changshu, Wei Jingxun, Zhang Zhiqiang, Tian Ni, Qin Gaowu, Zhao Xiang
School of Materials Science & Engineering, Northeastern University, Shenyang 110819, China.
Key Laboratory for Anisotropy and Texture of Materials, Northeastern University, Shenyang 110819, China.
Materials (Basel). 2022 May 7;15(9):3368. doi: 10.3390/ma15093368.
The fabricated Al-Zn-Mg-Cu alloy build has low mechanical properties due to the dissolution of strengthening precipitates back into the matrix during friction stir additive manufacturing (FSAM). Post-fabricated aging was considered an effective approach to improve the mechanical performance of the build. In this study, various post-fabricated aging treatments were applied in the underwater FSAM of Al-7.5 Zn-1.85 Mg-1.3 Cu-0.135 Zr alloy. The effect of the post-fabricated aging on the microstructure, microhardness, and local tensile properties of the build was investigated. The results indicated that over-aging occurred in the low hardness zone (LHZ) of the build after artificial aging at 120 °C for 24 h as the high density of grain boundaries, subgrain boundaries, dislocations, and AlZr particles facilitated the precipitation. Low-temperature aging treatment can effectively avoid the over-aging problem. After aging at 100 °C for 48 h, the average microhardness value of the build reached 178 HV; the yield strength of the LHZ and high hardness zone (HHZ) was 453 MPa and 463 MPa, respectively; and the ultimate tensile strength of the LHZ and HHZ increased to 504 MPa and 523 MPa, respectively.
在搅拌摩擦增材制造（FSAM）过程中，由于强化析出相重新溶解回基体，制造出的Al-Zn-Mg-Cu合金构件的力学性能较低。制造后时效处理被认为是提高构件力学性能的有效方法。在本研究中，对Al-7.5Zn-1.85Mg-1.3Cu-0.135Zr合金的水下FSAM应用了各种制造后时效处理。研究了制造后时效对构件微观结构、显微硬度和局部拉伸性能的影响。结果表明，在120℃人工时效24h后，构件的低硬度区（LHZ）发生了过时效，因为高密度的晶界、亚晶界、位错和AlZr颗粒促进了析出。低温时效处理可以有效避免过时效问题。在100℃时效48h后，构件的平均显微硬度值达到178HV；LHZ和高硬度区（HHZ）的屈服强度分别为453MPa和463MPa；LHZ和HHZ的抗拉强度分别提高到504MPa和523MPa。
