Transactions of Nonferrous Metals Society of China The Chinese Journal of Nonferrous Metals

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中国有色金属学报

ZHONGGUO YOUSEJINSHU XUEBAO

第15卷    第10期    总第79期    2005年10月

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文章编号: 1004-0609(2005)10-1594-08
微量Cr、 Mn、 Ti、 Zr细化7A55铝合金
铸锭组织的效果与机理
贺永东, 张新明

(中南大学 材料科学与工程学院, 长沙 410083)

摘 要:  采用光学显微镜、 扫描电镜及能谱分析术研究了复合添加微量Cr、 Mn、 Ti、 Zr细化7A55合金铸锭组织的效果和机理。结果表明: 复合添加0.04%Ti+0.17% Zr能在一定程度上细化7A55合金铸锭组织,复合添加0.20%Cr+0.20% Mn+0.03% Ti能够显著细化铸锭组织, 其细化机理为含有Cr、 Mn的原子团簇作为Al3Ti形核的基底促使α-Al成核; 复合添加微量0.04%Cr+0.04%Mn+0.03%Ti+0.18%Zr产生了极强烈的晶粒细化效果, 其细化机理为含有Cr、 Mn的原子团簇作为Al3Ti、 Al3Zr共同形核的基底使Al3(TixZr1-x)形核, Al3(TixZr1-x)使α-Al形核。 随着Cr、 Mn含量增加,铸锭晶粒向枝晶化、 粗大化方向发展。

 

关键字:  7A55铝合金;微量元素; 晶粒细化; 形核

Refinement mechanism of trace Cr, Mn, Ti and
Zr as cast 7A55 alloys
HE Yong-dong, ZHANG Xin-ming

School of Materials Science and Engineering,
Central South University, Changsha 410083, China

Abstract: The grain refinement effect and mechanism by addition of trace Cr, Mn, Ti and Zr in 7A55 cast alloy were studied by optical microscopy, scanning electron microscopy and energy dispersive spectrum(EDS). The results show that adding 0.04%Ti and 0.17%Zr can refine the grain to a certain degree. Joint addition of 0.20%Cr, 0.20%Mn and 0.03%Ti has strong grain refinement effect. The refinement mechanism is that atom clusters containing minor Cr and Mn act as substrate of Al3Ti particle, which nucleate α-Al. With joint addition of 0.04%Cr, 0.04%Mn, 0.03%Ti and 0.18%Zr, a remarkable grain refinement and a fine equiaxed grains are obtained. The refinement mechanism is that atom clusters containing trace Cr and Mn nucleate Al3Ti particles which nucleates Al3 (TixZr1-x), then nucleates α-Al. With increasing content of Cr and Mn in the alloy, the grains become coarse and dendritic.

 

Key words: 7A55 aluminium alloy; trace elements; grain refinement; nucleation

ISSN 1004-0609
CN 43-1238/TG
CODEN: ZYJXFK

ISSN 1003-6326
CN 43-1239/TG
CODEN: TNMCEW

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