工程科学学报，第39卷，第4期：502510,2017年4月 Chinese Journal of Engineering,Vol.39,No.4:502-510,April 2017 DOI:10.13374/j.issn2095-9389.2017.04.004:http://journals.ustb.edu.cn 活度”质疑 郭汉杰12)✉ 1)北京科技大学治金与生态工程学院，北京1000832)高端金属材料特种熔炼与制备北京市重点实验室，北京100083 ☒通信作者，E-mail:guohanjie@usth.edu.cn 摘要为研究二元系溶液中组元摩尔分数和气相中蒸气压的规律，考察了48个化合物在熔点固液相变的熔化熵变，发现 相变时没有发生显著的化合物分解.在假设二元系溶液中存在化合物分子的情况下，组元在全浓度范围符合拉乌尔定律，不 存在Lwis定义的“活度”；通过与MgSi、InSb和FeMn三个二元系实测活度结果对比，证实了计算的平衡摩尔分数即为活 度值，二元金属熔体不存在所谓“活度”的观点.推导了在二元系金属熔体存在一个金属间化合物条件下平衡的摩尔分数的 通用公式，以及相应的A,B或AB型金属间化合物的一般公式.将二元系溶液划分为大于纯组元熔点的温度、小于纯组元熔 点温度但高于液相线和低于液相线的三个区间，提出了适应不同区间的广义拉乌尔定律的关系式。 关键词活度：热力学；平衡体系：溶液 分类号TF02 Activity query GU0 Hanjie2》a 1)School of Metallurgical and Ecological Engineering,University of Science and Technology Beijing,Beijing 100083,China 2)Beijing Key Laboratory of Special Melting and Preparation of High-nd Metal Materials,Beijing 100083,China Corresponding author,E-mail:guohanjie@ustb.edu.cn ABSTRACT To investigate the laws relating to the mole fraction of a component in a binary solution and its vapor pressure,the en- tropies of dissolution from the solid phase to the liquid phase of 48 typical compounds were assessed and the compounds were confirmed to not decompose during the phase transition processes.Under the condition where a compound also exists in a binary liquid melt,both of the components in the whole concentration range obey Raoult's law.Specifically,there is no such thing as an "activity"as defined by Lewis.The so-called "activity"is actually the balance mole fraction in the case where all components in the system are considered by comparing with the measured activity data for Mg-Si,Sb-In,and Fe-Mn binary systems.It is verified that the calculated equili- brated mole fraction represents the activity,thereby the binary metallic melts involve no activity.In addition,a general formula is de- duced for the equilibrium mole fraction in the binary system in the case where the melt contains one intermetallic compound.In parti- cular,the cases corresponding to A B-type or AB-type intermetallic compounds were discussed.Finally,a broad sense Raoult's law was proposed that it is applicable in all three regions in binary solution divided by different temperatures:(I)the region corresponding to temperatures above the melting point of the component,(II)the region corresponding to temperatures lower than the melting point of the pure component but greater than the liquidus temperature,and (IIl)the region corresponding to temperatures lower than the lig- uidus temperature. KEY WORDS activity:thermodynamics:equilibrated systems;solution 活度，自Lewis0在1913年提出至今，已经100多 年的历史，为热力学的发展，特别是有溶液参加的化学 收稿日期：201604-26 基金项目：国家自然科学基金资助项目(51274031)工程科学学报，第 39 卷，第 4 期: 502--510，2017 年 4 月 Chinese Journal of Engineering，Vol． 39，No． 4: 502--510，April 2017 DOI: 10． 13374 /j． issn2095--9389． 2017． 04． 004; http: / /journals． ustb． edu． cn “活度”质疑 郭汉杰1，2)  1) 北京科技大学冶金与生态工程学院，北京 100083 2) 高端金属材料特种熔炼与制备北京市重点实验室，北京 100083 通信作者，E-mail: guohanjie@ ustb． edu． cn 摘 要 为研究二元系溶液中组元摩尔分数和气相中蒸气压的规律，考察了 48 个化合物在熔点固液相变的熔化熵变，发现 相变时没有发生显著的化合物分解． 在假设二元系溶液中存在化合物分子的情况下，组元在全浓度范围符合拉乌尔定律，不 存在 Lewis 定义的“活度”; 通过与 Mg--Si、In--Sb 和 Fe--Mn 三个二元系实测活度结果对比，证实了计算的平衡摩尔分数即为活 度值，二元金属熔体不存在所谓“活度”的观点． 推导了在二元系金属熔体存在一个金属间化合物条件下平衡的摩尔分数的 通用公式，以及相应的 A2B 或 AB 型金属间化合物的一般公式． 将二元系溶液划分为大于纯组元熔点的温度、小于纯组元熔 点温度但高于液相线和低于液相线的三个区间，提出了适应不同区间的广义拉乌尔定律的关系式． 关键词 活度; 热力学; 平衡体系; 溶液 分类号 TF02 Activity query GUO Han-jie1，2)  1) School of Metallurgical and Ecological Engineering，University of Science and Technology Beijing，Beijing 100083，China 2) Beijing Key Laboratory of Special Melting and Preparation of High-end Metal Materials，Beijing 100083，China Corresponding author，E-mail: guohanjie@ ustb． edu． cn ABSTＲACT To investigate the laws relating to the mole fraction of a component in a binary solution and its vapor pressure，the en￾tropies of dissolution from the solid phase to the liquid phase of 48 typical compounds were assessed and the compounds were confirmed to not decompose during the phase transition processes． Under the condition where a compound also exists in a binary liquid melt，both of the components in the whole concentration range obey Ｒaoult’s law． Specifically，there is no such thing as an“activity”as defined by Lewis． The so-called“activity”is actually the balance mole fraction in the case where all components in the system are considered by comparing with the measured activity data for Mg--Si，Sb--In，and Fe--Mn binary systems． It is verified that the calculated equili￾brated mole fraction represents the activity，thereby the binary metallic melts involve no activity． In addition，a general formula is de￾duced for the equilibrium mole fraction in the binary system in the case where the melt contains one intermetallic compound． In parti￾cular，the cases corresponding to A2B--type or AB--type intermetallic compounds were discussed． Finally，a broad sense Ｒaoult’s law was proposed that it is applicable in all three regions in binary solution divided by different temperatures: ( I) the region corresponding to temperatures above the melting point of the component，( II) the region corresponding to temperatures lower than the melting point of the pure component but greater than the liquidus temperature，and ( III) the region corresponding to temperatures lower than the liq￾uidus temperature． KEY WOＲDS activity; thermodynamics; equilibrated systems; solution 收稿日期: 2016--04--26 基金项目: 国家自然科学基金资助项目( 51274031) 活度，自 Lewis［1］在 1913 年提出至今，已经 100 多 年的历史，为热力学的发展，特别是有溶液参加的化学