Effect of solution time in T6 heat treatment on microstructure and hardness of a directionally solidified Al-Si-Cu alloy
Effect of solution time in T6 heat treatment on microstructure and hardness of a directionally solidified Al-Si-Cu alloy
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DOI：
10.1016/j.jallcom.2016.05.099
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发表时间：
2016-10-25
影响因子：
6.2
通讯作者：
Garcia, Amauri
中科院分区：
文献类型：
--
作者：
Costa, Thiago A.;Dias, Marcelino;Garcia, Amauri
本文研究了Al-5.5wt%Si-3.0wt%Cu合金在T6热处理过程中固溶时间对二次枝晶间距（λ（2））、Si颗粒和Al_2Cu金属间化合物的形态和分布的影响，以及由此产生的对显微硬度的影响。一个定向凝固（DS）铸件先前获得使用水冷装置，这允许一个宽范围的冷却速率（（T）点）与样品具有相当不同的微观结构参数特征。本文提出了一个关于λ（2）与（T）随点变化的实验增长律。然后在DS样品上进行T6热处理不同的溶解时间：在490 +/-2 ° C下8小时和5小时，然后在温水（60 +/-2 ° C）中淬火，在155 +/-2 ° C下老化5小时并空气冷却。微观结构表征（光学和扫描电子显微镜）表明，当溶解时间从5 h增加到8 h时，λ（2）仅受影响（与DS铸造样品相比）。与此相反，Si和Al 2Cu颗粒的形态和分布的显着影响被示出发生。最高的硬度被示出与经受5小时处理的样品相关联，具有最低的λ（2）和Si和Al 2Cu颗粒的适当改性。(C)2016爱思唯尔B. V.保留所有权利。
An experimental investigation on the role of solution time during the T6 heat treatment on the scale of the secondary dendrite arm spacing (lambda(2)), morphology and distribution of Si particles and Al2Cu intermetallics and the resulting effect on microhardness of Al-5.5 wt% Si-3.0 wt% Cu alloy samples is performed. A directionally solidified (DS) casting was previously obtained using a water-cooled apparatus, which permitted a wide range of cooling rates ((T) over dot) to be associated with samples having quite different microstructural parametric features. An experimental growth law relating lambda(2) to (T) over dot is proposed. The T6 heat treatment was then carried out on the DS samples for different solution times: 8 h and 5 h at 490 +/- 2 degrees C, followed by quenching in warm water (60 +/- 2 degrees C), ageing for 5 h at 155 +/- 2 degrees C and air-cooling. The microstructure characterization (optical and scanning electron microscopies) has shown that lambda(2) was only affected (when compared with those of the DS casting samples) when the solution time increased from 5 h to 8 h. In contrast, significant influences on the morphology and distribution of both Si and Al2Cu particles are shown to occur. The highest hardness is shown to be associated with a sample subjected to the 5 h treatment, having lowest lambda(2) and appropriate modification of Si and Al2Cu particles. (C) 2016 Elsevier B.V. All rights reserved.