Fracture behavior of aged Mg-10Gd-3Y-0.6Zr alloy under tension loading
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摘要:
研究了時效顯微組織對Mg-10Gd-3Y-0.6Zr合金斷裂行為的影響.結果表明:473K低溫時效時,析出相小而密,由晶界析出相(GBP)引發的微裂紋在晶界處產生并沿晶內的擇優取向擴展;溫度達到523K時,GBP長大,應力集中僅在某些大尺寸GBP處出現,并引發GBP與基體分離,而產生微孔,微孔的聚集與長大導致了合金的斷裂.微裂紋沿著孿晶與基體的界面擴展,在斷口形成平滑刻面,而GBP的存在會加劇這一趨勢.時效溫度升高后,孿晶與GBP數量減少,滑移變形加劇,導致平滑刻面數量減少.
Abstract:The effect of aging microstructure on the fracture behavior of Mg-10Gd-3Y-0.6Zr alloy was investigated.The results show that precipitates in the alloy after low temperature aging at 473 K are finer and denser.Microcracks nucleate at grain boundaries due to grain boundary precipitations (GBPs),and then propagate transgranularly along the preferred orientation.When the aging temperature increases to 523 K,the size of GBPs enlarges.Microvoids nucleate by interface debonding between GBPs and the matrix which is caused by stress concentration at large GBPs;subsequently,their coalescence and growth result in final fracture.Otherwise,smoothing facets on the fracture surface form by microcracks propagating along the interfaces between twins and the matrix,and this tendency is intensified due to the existence of GBPs.When the aging temperature increases,the smoothing facets reduce as the twins and GBPs decrease and the slip deformation intensifies.
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Key words:
- magnesium alloys /
- precipitation /
- tensile properties /
- microstructure /
- fracture
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