Effects of trace elements (Y and Ca) on the eutectic Ge in Al-Ge based alloys

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• 作者：J.H. Li^a ; ^{jie-hua.li@hotmail.com" class="auth_mail" title="E-mail the corresponding author} ; N. Wanderka^b ; Z. Balogh^c ; P. Stender^c ; H. Kropf^b ; M. Albu^d ; Y. Tsunekawa^e ; F. Hofer^d ; G. Schmitz^c ; P. Schumacher^a ; ^f
• 关键词：Al&ndash ; Ge alloy ; Segregation ; Solute entrainment ; Eutectic solidification ; HAADF-STEM ; Atom probe tomography
• 刊名：Acta Materialia
• 出版年：2016
• 出版时间：1 June 2016
• 年：2016
• 卷：111
• 期：Complete
• 页码：85-95
• 全文大小：4536 K

文摘

Effects of trace elements (0.2Y and 0.2Ca (wt%) on the eutectic Ge in high purity Al–20Ge (wt%) alloys were investigated by multi-scale microstructure characterization techniques. Particularly, the distribution of trace elements (Y and Ca) within the eutectic Ge and/or at the interface between eutectic Ge and eutectic Al was investigated by atomic resolution high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) imaging and atom probe tomography (APT). The combined investigations indicate Al–Y and Al–Ca co-segregations. Such co-segregations change significant morphology and growth of the eutectic Ge. In addition, large Al₂Ge₂Y and Al₂Ge₂Ca phases were also measured. The modification of eutectic Ge is discussed in terms of previously postulated modification mechanisms: twin plane re-entrant edge growth mechanism, impurity-induced twinning, and growth restriction of eutectic Ge.