Grain refinement mechanisms of hypoeutectic Al-Si alloys
Grain refinement mechanisms of hypoeutectic Al-Si alloys
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DOI：
10.1016/1359-6454(96)00021-3
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发表时间：
1996-09-01
期刊：
影响因子：
9.4
通讯作者：
Gruzleski, JE
中科院分区：
文献类型：
--
作者：
Mohanty, P;Gruzleski, JE
亚共晶Al-Si合金晶粒细化机理的一般概念是从变形合金晶粒细化机理的一般概念引入的，没有考虑硅含量的影响。在本研究中，通过将合成的TiB_2晶体直接引入到Al-Si熔体中，实验模拟了Al-Si铸造合金的晶粒细化实践。为了探索新一代Al-Ti-C中间合金在这些合金中的可能用途，还研究了合成TiC的行为。实验结果表明，在硅的存在下，TiC晶体在铝熔体中是高度不稳定的。单独的TIB 2晶体不使α-相成核，而在存在溶解的Ti的情况下，在TiB 2上形成三元Al-Ti-Si界面层，其随后通过包埋反应使α-Al成核。然而，由于过冷温度的急剧下降，晶粒细化的效率大大降低。理论分析表明，当硼以超过TiB 2化学计量加入时，或者简单地作为AlB 2加入时，通过共晶反应发生晶粒细化。版权所有（C）1996 Acta Metallurgica Inc.
The general concept of the grain refinement mechanism in hypoeutectic Al-Si alloys has been adopted from that in wrought alloys without consideration of the influence of the silicon content. In the present investigation the commerical grain refinement practice in Al-Si foundry alloys has been experimentally simulated by introducing synthetic TiB2 crystals directly into Al-Si melts. To explore the possible use of a new generation of Al-Ti-C master alloys in these alloys, the behaviour of synthetic TiC has also been studied. Experimental findings indicate that in the presence of Si, TiC crystals are highly unstable in aluminium melts. TIB2 crystals alone do not nucleate the alpha-phase, whereas in the presence of dissolved Ti a ternary Al-Ti-Si interfacial layer is formed on the TiB2 which subsequently nucleates the alpha-Al. via a peritectic reaction. However, due to a drastic decrease ill the peritectic temperature, the efficiency of grain refinement is greatly reduced. A theoretical analysis indicates that when boron is added in excess of TiB2 stoichiometry, or simply as AlB2, grain refinement occurs by a eutectic reaction. Copyright (C) 1996 Acta Metallurgica Inc.