In-situ investigation of incipient melting in a 319 type Al alloy using laser scanning confocal microscopy
In-situ investigation of incipient melting in a 319 type Al alloy using laser scanning confocal microscopy
复制标题
使用激光扫描共焦显微镜对 319 型铝合金的初熔进行原位研究
DOI：
10.1016/j.matchar.2018.05.012
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发表时间：
2018
影响因子：
4.7
通讯作者：
M. Barati
中科院分区：
文献类型：
--
作者：
A. Lombardi;Wangzhong Mu;C. Ravindran;N. Dogan;M. Barati
改性的319铝合金系统已广泛用于汽车动力总成应用的精密砂型铸造，如发动机缸体和气缸盖，显著提高了车辆的燃油效率。然而，在Al合金的高温加工（例如热处理和热加工工艺）中的问题是第二相的初期熔化，这对机械性能是有害的。在这项研究中，激光扫描共聚焦显微镜（LSCM）技术被用于分析原位变化的微观结构作为一个结果的初始熔化。使用光学显微镜、SEM和EDX在LSCM中高温暴露之前和之后进行微观结构分析。结果表明，Al-Al 2Cu-Al 5 Mg 8 Cu 2Si 6三元共晶团的初熔是由共晶团附近的Al枝晶表面形成的液膜快速扩散而引发的。成膜后，三元共晶团完全熔化。初熔也导致局部变化的组合物中的枝晶间的通道支持的变化，从共晶到粗块状的Al-Cu-Ni和Si颗粒的组合，和超细共晶的集群形态。
The modified 319 Al alloy system has been used extensively in precision sand casting of automotive powertrain applications such as engine blocks and cylinder heads, with significant improvement in vehicle fuel efficiency. However, a concern in elevated temperature processing of Al alloys, such as heat treatment and hot working processes, is incipient melting of secondary phases, which is deleterious to mechanical properties. In this study, the laser scanning confocal microscopy (LSCM) technique was used in the analysis of in-situ changes in microstructure as a result of incipient melting. Microstructural analysis was carried out prior to and following elevated temperature exposure in the LSCM using optical microscopy, SEM and EDX. The results suggest that incipient melting of the Al-Al2Cu-Al5Mg8Cu2Si6ternary eutectic clusters was initiated by the formation of a liquid film which propagated rapidly from the eutectic clusters, coating the Al dendrites in regions adjacent to the eutectic clusters. Following film formation, the ternary eutectic clusters melted completely. Incipient melting also resulted in a localized change in composition in the interdendritic channels as supported by a change in cluster morphology from eutectic to a combination of coarse blocky Al-Cu-Ni and Si particles, and ultra-fine eutectic.