首页> 外文会议>International Conference on Processing amp; Manufacturing of Advanced Materials; 20060704-08; Vancouver(CA) >Non-equilibrium solute partitioning and microstructure formation in rapidly solidified Al-Sm alloys
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Non-equilibrium solute partitioning and microstructure formation in rapidly solidified Al-Sm alloys

机译:快速凝固的Al-Sm合金的非平衡溶质分配和微观结构形成

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摘要

A critical issue, central to microstructural selection in highly driven systems, is the role of nonequilibrium solute partitioning and the formation of metastable phases. When local chemical equilibrium breaks down at very high undercoolings, solidification dynamics are influenced by limitations to atomic attachment kinetics, decreasing solute diffusivities, changing thermodynamic driving forces, and the energetics of ordering or clustering in the liquid phase. The scope of the current study is to employ free-jet melt spinning along with advanced e-beam, x-ray diffraction techniques to investigate the degree of solute partitioning and metastable phase formation during rapid solidification of Al-Sm alloys with compositions at or near the Al-rich eutectic (15wt.% or 3 at.%). At all melt spinning rates employed (10-40m/s), solidification morphologies consist of the Al (fcc) and Al_(11)Sm_3 (tetragonal) phases. Certain morphological transitions occur through the thickness of the ribbon, indicating a change in the prevailing cooling conditions as solidification proceeds. In addition, x-ray diffraction analysis indicates that the Sm content in the fcc Al phase is well above that given by local two-phase (fcc+Iiquid) equilibrium.
机译:在高驱动系统中进行微结构选择的关键问题是非平衡溶质的分配和亚稳相的形成。当局部化学平衡在非常高的过冷度下破裂时,凝固动力学会受到原子附着动力学的局限性,溶质扩散性降低,热力学驱动力变化以及液相中有序或成簇的能量的影响。当前研究的范围是采用自由射流熔体纺丝技术以及先进的电子束,X射线衍射技术来研究快速凝固的Al-Sm合金中或接近附近的成分时溶质分配和亚稳态相形成的程度富铝共晶(15 wt。%或3 at。%)。在所有采用的熔融纺丝速率下(10-40m / s),凝固形态均由Al(fcc)和Al_(11)Sm_3(四方)相组成。在薄带的厚度上会发生某些形态转变,这表明随着凝固的进行,主要的冷却条件发生了变化。另外,X射线衍射分析表明,fcc Al相中的Sm含量远高于局部两相(fcc + Iiquid)平衡给出的Sm含量。

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