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论文类型：期刊论文

发表时间：2015-02-15

发表刊物：JOURNAL OF ALLOYS AND COMPOUNDS

收录刊物：SCIE、EI

卷号：622

页面范围：871-879

ISSN号：0925-8388

关键字：Primary silicon; Eutectic silicon; Strontium modification; Zn-27Al-3Si alloy; Mechanical properties

摘要：The evolution of silicon phase and mechanical properties of Zn-27Al-3Si alloy with Sr addition were investigated. The results showed that primary Si crystals were gradually modified from polygonal, plate-like and star-like to larger nodular with increasing the addition contents of Sr. A bimodal distribution of eutectic Si crystals was found. One was the coarse eutectic (CE) Si nucleating and growing from the primary Si crystals, the other was the fine eutectic (FE) Si nucleating at other sites (not primary Si). The average size and aspect ratio of FE Si crystals significantly decreased and whose morphology was transformed from a coarser plate-like structure to a fine fibrous structure with more branches with increasing Sr content. Through electron probe microanalysis mapping (EPMA) and cooling curves, it was concluded that the nodular primary Si crystals nucleated and grew by producing a large undercooling (about 40 degrees C) and preferential attachment of Sr to silicon phase. The mechanical properties were investigated by tensile test with various concentration of Sr. It was found that the ultimate tensile strength (UTS) and elongation (EI) increased by 62.6% and 162%, respectively. The improvements in UTS and EI were attributed to the morphology change of silicon phase as well as the improved feeding solidification shrinkage. (C) 2014 Elsevier B.V. All rights reserved.