Stable and metastable phase equilibria in the chemical interaction between aluminium and silicon carbide
Stable and metastable phase equilibria in the chemical interaction between aluminium and silicon carbide
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DOI：
10.1007/bf01045395
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发表时间：
1990-03
影响因子：
4.5
通讯作者：
J. Viala;P. Fortier;J. Bouix
中科院分区：
文献类型：
--
作者：
J. Viala;P. Fortier;J. Bouix
对Al-C-Si三元系在常压和1900K温度下进行了实验研究，建立了基于Al-C-Si三元系稳定相平衡和亚稳态相平衡的热力学模型，以期对Al-C-Si三元系中铝与碳化硅之间的化学作用提供一般性的描述。根据这个模型，铝和碳化硅在低于923K的每一个温度下都处于热力学平衡状态。在923±3K，即低于纯铝熔点10K时，Al-C-Si系统发生了准包晶不变量转变。在这种转变中，固体铝与碳化硅反应生成Al4C3和三元(Al-C-Si)液相。该液相碳含量很低，硅含量为1.5±0.4at%。从923K到1620K，铝与过量的碳化硅发生部分反应，形成了一个由碳化硅、碳化铝和富铝(Al-C-Si)三元液相组成的亚稳单变量平衡。该液相L的碳含量很低，而硅含量随着温度的升高而增加，从923K的1.5at%增加到1620K的16.5±1at%。这些平衡一方面涉及到SiC、Al_4SiC_4和液相L‘，另一方面涉及到Al_4SiC_4、Al_4C_3和液相L“。前者是稳定的均衡，后者是亚稳态的。当温度高于约2200K时，后一个亚稳平衡被包括三元碳化物Al8SiC7在内的两个单变量稳定相平衡所取代。
An experimental investigation was carried out on the Al-C-Si ternary system under atmospheric pressure and at temperatures up to 1900 K. From the results obtained, a thermodynamic model based on stable and metastable phase equilibria in the Al-C-Si ternary system was set up in order to provide a general description of the chemical interaction between aluminium and SiC. According to this model, aluminium and SiC are in thermodynamic equilibrium at every temperature lower than 923 K. At 923±3 K, i.e. at 10 K below the melting point of pure aluminium, a quasiperitectic invariant transformation occurs in the Al-C-Si system. In this transformation, solid aluminium reacts with SiC to give Al4C3and a ternary (Al-C-Si) liquid phase. The carbon content of this liquid phase is very low; its silicon content is 1.5±0.4 at%. From 923 to about 1620 K, aluminium partially reacts with an excess of SiC, leading to a metastable monovariant equilibrium involving SiC, Al4C3and an aluminium-rich (Al-C-Si) ternary liquid phase, L. The carbon content of this liquid phase, L, remains very low whereas its silicon content increases with temperature from 1.5±0.4 at% at 923 K to 16.5±1 at% at 1620 K. In the temperature range 1670 to 1900 K, two other three-phased monovariant equilibria can be reached by reacting aluminium and SiC. These equilibria involve on the one hand SiC, Al4SiC4and a liquid phase, L′, and on the other hand, Al4SiC4, Al4C3and a liquid phase, L″. The former is a stable equilibrium, the latter is a metastable one. At temperatures higher than about 2200 K, the latter metastable equilibrium is replaced by two monovariant stable phase equilibria including the ternary carbide Al8SiC7.