Study of twinned dendrite growth stability
Study of twinned dendrite growth stability
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DOI：
10.1016/j.scriptamat.2009.04.016
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发表时间：
2009-08
影响因子：
6
通讯作者：
M. A. Salgado-Ordorica;J. Valloton;M. Rappaz
中科院分区：
文献类型：
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作者：
M. A. Salgado-Ordorica;J. Valloton;M. Rappaz
在一定的热条件下（G = 1× 104 Km −1，νs = 1×10− 3 ms −1），铝合金中会出现孪晶枝晶，并且在熔体中也存在对流的情况下，孪晶枝晶可以长过规则的柱状枝晶。为了检查这种形态的稳定性，定向凝固的Al-Zn孪晶样品在布里奇曼炉中部分重熔，然后在受控条件下再凝固，对流最小。结果发现，虽然孪晶面保持稳定，在部分重熔，非孪晶枝晶在凝固过程中再生。它们具有由孪晶和非孪晶“籽晶”区域的晶体取向给出的晶体取向，并且沿着倾向于正常试样的那些择优方向沿着生长。
Under certain thermal conditions (G≈1×104Km−1, νs≈1×10−3ms−1), 〈110〉 twinned dendrites appear in aluminum alloys and can overgrow regular columnar dendrites, provided that some convection is also present in the melt. In order to check the stability of such morphologies, directionally solidified twinned samples of Al–Zn were partially remelted in a Bridgman furnace and then resolidified under controlled conditions, with minimal convection. It was found that, although twin planes remain stable during partial remelting, non-twinned dendrites regrow during solidification. They have a crystallographic orientation given by those of the twinned and untwinned “seed” regions, and grow along preferred directions that tend to be those of normal specimens.