The influence of T6 treatment on fracture behavior of hypereutectic Al-Si HPDC casting alloy

JOURNAL OF ALLOYS AND COMPOUNDS

卷:731

Article

Yu, Wenbo¹  Zhao, Hongbin²  Wang, Lei^3,4  Guo, Zhipeng⁵  Xiong, Shoumei⁵ 

[1] Beijing Jiaotong Univ, Ctr Mat Sci & Engn, Sch Mech & Elect Control Engn, Beijing 100044, Peoples R China

[2] Gen Res Inst Nonferrous Met, State Key Lab Adv Mat Smart Sensing, Beijing 100088, Peoples R China

[3] Chinese Acad Sci, Key Lab Cryobiomed Engn, Tech Inst Phys & Chem, Beijing 100190, Peoples R China

[4] Chinese Acad Sci, Key Lab Cryogen, Tech Inst Phys & Chem, Beijing 100190, Peoples R China

[5] Tsinghua Univ, Lab Adv Mat Proc Technol, Minist Educ, Beijing 100084, Peoples R China

关键词: Hypereutectic Al-Si alloy;    Die casting;    In-situ observation;    Crack propagation;   

DOI  :  10.1016/j.jallcom.2017.10.074

来源: Elsevier

【 摘 要 】

The strength and fracture behavior of hypereutectic A390 alloys produced by high pressure die casting have been studied in relationship with the microstructural evolution before and after T6 treatment. Due to the transformation of plate-like eutectic Si particles into granular particles and dissolution of Al2Cu into Al matrix, T6 treatment could ameliorate the mechanical properties of as-cast A390 specimens. Tensile fractographs reveal primary Si particles detached from Al matrix in as-cast A390 specimen, while cleavage fracture happened in primary Si after T6 treatment. In bending test, EBSD indicates that Si particles did not break in twinning boundaries, whereas, the cracks were mainly perpendicular to (101) and (001) lattice planes. In-situ observation indicates that cracks were firstly initiated in primary Si particles in both as-cast and T6 treated specimens. Subsequently, the cracks connected along Al grain boundaries among primary Si particles in as-cast specimen, while they connected through the slip lines occurring in Al grains after T6. (C) 2017 Elsevier B.V. All rights reserved.

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