文章信息/Info

Title:

Thermodynamic Principles for the Solidification of Multi Component Alloys

作者:

介萬(wàn)奇��

 (西北工業(yè)大學(xué)材料學(xué)院 凝固技術(shù)國(guó)家重點(diǎn)實(shí)驗(yàn)室，陜西 西安 710072）

Author(s):

JIE Wanqi

（State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi�餫n 710072, China)

關(guān)鍵詞:

多元多相合金; 凝固; 相圖計(jì)算技術(shù)

DOI:

10.7502/j.issn.1674-3962.2012.12.04

文獻(xiàn)標(biāo)志碼:

A

摘要:

以發(fā)展多元多相合金的凝固理論為目標(biāo)，探討了多組元合金自由能描述方法及其凝固過(guò)程的熱力學(xué)平衡條件。多組元合金的自由能是由各組成元素的自由能、原子的組合排列引起熵的變化決定的理想混合自由能和由原子間交互作用引起的附加自由能三部分決定的。其中附加自由能的描述是難點(diǎn)，通常通過(guò)實(shí)驗(yàn)結(jié)果的擬合獲得。固相的析出條件可通過(guò)自由能最低的熱力學(xué)原理預(yù)測(cè)，而固相和液相成分的相關(guān)性則可通過(guò)化學(xué)位相等的熱力學(xué)原理計(jì)算。在實(shí)際應(yīng)用中，可以借鑒相圖計(jì)算方法進(jìn)行凝固過(guò)程的熱力學(xué)分析，進(jìn)而獲得相圖精細(xì)結(jié)構(gòu)的數(shù)值計(jì)算結(jié)果。以Al�睲g�睸i合金為算例，進(jìn)行了三元合金熱力學(xué)平衡條件的分析。以該熱力學(xué)平衡條件計(jì)算結(jié)果為基礎(chǔ)，引入對(duì)固相和液相中擴(kuò)散過(guò)程的分析，則可實(shí)現(xiàn)多組元合金凝固路徑的預(yù)測(cè)。

Abstract:

As the fundamental principles for the solidification of multi�瞔omponent alloys, the thermodynamic equilibrium conditions between the melt and solid phases were discussed, based on description model of Gibbs free energy for different phases. The Gibbs free energy of a multi�瞔omponent alloy in a specialized phase is composed of three terms, i.e. the contributions of each pure elements, the energy introduced due to the ideal mixture of all elements, and extra energy caused by the chemical interaction among different elements. The last term is the most complicated one for description, which is normally fitted based on the experimental results. Solidification order of different phases can be predicated by comparing the Gibbs energy of different phases, and the solidification path can be evaluated by equilibrium of the chemical potentials of liquid and solid phases. As a practical method, Calphad method can be adopted for the numerical calculation in the equilibrium condition predications. The reliability of the method was proved by using the method for Al�睲g�睸i system. Combining the above thermodynamic method with diffusion analyses, the solidification path can be evaluated for any real solidification process.��