Comparison of microstructural evolution of 7075 aluminum alloy fabricated by SIMA and RAP
Comparison of microstructural evolution of 7075 aluminum alloy fabricated by SIMA and RAP
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SIMA和RAP制备的7075铝合金显微组织演变比较
DOI：
10.1016/j.jmatprotec.2016.06.020
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发表时间：
2016-12-01
影响因子：
6.3
通讯作者：
Nie, Xi
中科院分区：
文献类型：
--
作者：
Jiang, Jufu;Wang, Ying;Nie, Xi
通过应变诱导熔化活化（SIMA）和再结晶与部分重熔（RAP）制造出了 7075 铝合金的半固态坯料。分析了等温温度和浸泡时间对 7075 铝合金微观结构的影响。结果表明，随着等温温度的升高，浸泡 20 分钟的 SIMA 和 RAP 所制造的 7075 铝合金的平均晶粒尺寸先增大后减小。就 SIMA 而言，当等温温度从 580 摄氏度升至 610 摄氏度时，晶粒尺寸增大，而等温温度高于 610 摄氏度时，固体晶粒尺寸减小。就 RAP 而言，等温温度从 580 摄氏度升高到 600 摄氏度会导致晶粒尺寸增大，进一步升高又会导致晶粒尺寸减小。与 SIMA 显微结构相比，RAP 显微结构中的球形晶粒更大，球化温度更低，球化效果更好。在 590 摄氏度和 600 摄氏度条件下延长浸泡时间，微观结构中的晶粒会发生粗化。RAP 和 SIMA 制造高质量半固体浆料所需的最佳浸泡时间为 20 分钟。颗粒凝聚和奥斯特瓦尔德熟化同时作用于颗粒的粗化。在 590 摄氏度和 600 摄氏度下制造的 SIMA 微结构中，粗化率常数分别为 316 μm(3)s(-1)和 402 μm(3)s(-1)；而在 RAP 微结构中，粗化率常数分别为 329 μm(3)s(-1)和 393 μm(3)s(-1)。与 SIMA 相比，RAP 微结构在 590 摄氏度时的粗化率略高，但在 600 摄氏度时的粗化率略低。(C) 2016 Elsevier B.V. 版权所有。保留所有权利。
Semisolid billets of 7075 aluminum alloy were fabricated by strain induced melting activated (SIMA) and recrystallization and partial remelting (RAP). Effect of isothermal temperature and soaking time on microstructure of fabricated 7075 aluminum alloys was analyzed. The results show that average grain sizes of 7075 aluminum alloys fabricated by SIMA and RAP soaked for 20 min firstly increased and then decreased with increasing isothermal temperature. As to SIMA, when isothermal temperature increased from 580 degrees C to 610 degrees C, grain size increased and an isothermal temperature above 610 degrees C led to a decrease of solid grain size. For RAP, increasing isothermal temperatures from 580 degrees C to 600 degrees C led to an increase of grain size and further increase led to a decrease. Larger spheroidal grains, lower spheroidization temperature and better spheroidization effect were obtained in the RAP microstructure in comparison to the SIMA microstructure. Coarsening of grains occurred in the microstructure while extending soaking time at 590 degrees C and 600 degrees C. Increasing isothermal temperature reduced spheroidization time. An optimal soaking time of 20 min is required for RAP and SIMA to fabricate high-quality semisolid slurry. Coalescence of grains and Ostwald ripening operated simultaneously in coarsening of grains. The coarsening rate constants are 316 mu m(3) s(-1) and 402 mu m(3) s(-1) respectively in the SIMA microstructure fabricated at 590 degrees C and 600 degrees C. The coarsening rate constants of 329 mu m(3) s(-1) and 393 mu m(3) s(-1) were achieved in the RAP microstructure. The RAP microstructure exhibited a slightly higher coarsening rate at 590 degrees C, but a slightly lower coarsening rate at 600 degrees C as compared to SIMA. (C) 2016 Elsevier B.V. All rights reserved.