论材料非晶形成中的焓与熵:竞争亦或协同?  

On glass formation thermodynamics: Enthalpy vs. Entropy

作　　者：王利民[1] 刘日平[1] 田永君[1] Wang Li-Min;Liu Ri-Ping;Tian Yong-Jun(State Key Laboratory of Metastable Materials Science and Technology,College of Materials Science and Engineering,Yanshan University,Qinhuangdao 066004,China)

机构地区：[1]燕山大学材料科学与工程学院,亚稳材料制备技术与科学国家重点实验室,秦皇岛066004

出　　处：《物理学报》2020年第19期180-197,共18页Acta Physica Sinica

基　　金：国家自然科学基金创新研究群体科学基金(批准号:51421091);国家重点研发计划(批准号:2018YFA0703602);国家自然科学基金(批准号:51801174);河北省高层次人才资助项目(批准号:BJ2018021)资助的课题.

摘　　要：液固Gibbs自由能差是决定材料非晶转变的热力学关键因素,但该参量在预测非晶转变和指导非晶成分设计方面仍有一些基本问题有待解决.其中,一个关键问题是:作为Gibbs能差的两个核心要素,焓与熵,二者在决定和控制非晶转变中关系并不明确.基于课题组系列研究结果,本文就焓与熵在材料非晶转变中的协同性与独立性问题进行了全面探讨,发现二者在决定非晶形成上具有很强的相关性.理论分析和实验测量相结合,展示了材料熔化熵与熔点粘度、混合焓等多个非晶形成经典参量之间的内在关联,证实熔化熵与材料非晶形成之间的密切关联;并从多个角度证实材料低熔化熵有利于非晶形成,纠正了传统上基于经典形核理论得出的高熔化熵有利于非晶形成的认识.研究也发现,决定非晶形成的关键动力学与热力学参量,如粘度和混合焓,均可通过熔化熵得到表达.进而论证了熔化熵在评估非晶形成、指导非晶成分设计中的可靠性和有效性,由此提出熔化熵可作为理解指导材料非晶形成的代表性热力学参量.系列成果为发展非晶形成热力学、深入理解材料非晶形成提供了参考与思路.Glass formation thermodynamics usually concerns the liquid-crystal Gibbs free energy difference.But,in practice,its efficiency in predicting the occurrence of the glass transition of materials and guiding the composition design is quite quantitative.In particular,it remains to be clarified to understand the relationship between and the contributions to the two fundamental quantities of enthalpy and entropy involved herein.In this paper,we study the relation between the enthalpy and the entropy involved in glass formation of various materials,and find that they are strongly correlated with each other.Theoretical and experimental analyses indicate the intrinsic correlation of the entropy of fusion with other key parameters associated with glass formation like melting viscosity and enthalpy of mixing,which confirms the close relation between the entropy of fusion and glass formation.Close inspection finds that the low entropy of fusion benefits the glass formation.Owing to the fact that the two glass-formation key variables of viscosity and enthalpy can be addressed by the entropy of fusion,we propose that the entropy of fusion be able to serve as a representative thermodynamic quantity to understand the glass formation in materials.The reliability in understanding the glass formation in terms of entropy of fusion is further verified.The studies provide a new reference for developing the glass formation thermodynamics.

关 键 词：非晶转变 非晶形成 相变热力学 

分 类 号：TB30[一般工业技术—材料科学与工程]