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论文类型：期刊论文

发表时间：2015-11-15

发表刊物：MATERIALS & DESIGN

收录刊物：SCIE、EI、Scopus

卷号：85

页面范围：724-732

ISSN号：0264-1275

关键字：In-situ composites; Grain refinement; Eutectic modification; Mechanical properties; Bimodal effect

摘要：In this work, in-situ A356-2.5 wt.% TiB2 composites were fabricated via a re-melting and diluting (RD) approach. The effects of lanthanum (La) on the microstructures and mechanical properties of the composites were investigated.The results demonstrated that the addition of La can, simultaneously, refine the second dendrite arm spacing (SDAS) of the alpha-Al grains and modify the coarse lamellar eutectic Si into fine fibrous particles. The optimum addition levels for refinement and modification lay at 0.1 wt.% and 0.8 wt.%, respectively, due to the distinct mechanisms between the two Since the resultant mechanical properties are a combined function of refinement and modification, the tensile properties of the composites show a bimodal distribution with the first peak value at 0.1 wt.% and the latter one at 0.8 wt.% La, in accordance with the optimum refinement and modification, respectively. (C) 2015 Elsevier Ltd. All rights reserved