On the characterization of microstructure and fracture in a high-pressure die-casting Al-10 wt%Si alloy

• Published in: Progress in natural science Vol. 30; no. 2; pp. 221 - 228
• Main Authors: Jiao, Xiangyi, Liu, Chaofeng, Wang, Jun, Guo, Zhipeng, Wang, Junyou, Wang, Zhuoming, Gao, Junming, Xiong, Shoumei
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.04.2020; School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China%School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China; Key Laboratory for Advanced Materials Processing Technology, Tsinghua University, Beijing China%Hong Bang Die Costing (NanTong) CO.,LTD China
• Subjects: Fracture; High-pressure die-casting; Hypoeutectic Al-10Si; Microstructure heterogeneity; Fracture; Microstructure heterogeneity; High-pressure die-casting; Hypoeutectic Al-10Si
• ISSN: 1002-0071
• DOI: 10.1016/j.pnsc.2019.04.008

Microstructure and fracture behavior in a high-pressure die-casting Al-10 wt%Si alloy have been investigated using optical microscope (OM), scanning electron microscope (SEM) and a high-resolution laboratory computed tomography (CT). The results showed that a typical heterogeneous microstructure of the alloy comprised α-Al rich region, eutectic silicon band region and porosity. The microstructure patterns highly dependent on fluid convection and rapid solidification. Under high filling speed, externally solidified crystals (ESCs) and the growing dendrites migrated in center and formed α-Al rich region. Si particles was discharged and enriched in the final solidified liquid, forming eutectic silicon band. Hard Si particles and brittle Fe-rich phases served as obstacles prevented dislocation migration, causing local stress concentration. Due to large movable slip systems in α-Al rich region, the propagation path of the crack was greatly extended. Net-shrinkage that induced by dense impinging dendrites led to the microcracks along the boundary of dendrites which promoted intergranular fracture. [Display omitted] •The failure mechanism of a high-pressure die-casting Al-10 wt%Si alloy is studied.•Laboratory CT provides a new method for analyses of 3-D fracture.•α-Al rich zone and eutectic silicon-rich zone play a major role in crack growth.