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Atomic volumes and volume functions for ag-cu alloys

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Science China(Technological Sciences) 1998年第2期41卷 157-168页

作者：谢佑卿张晓东 Department of Materials Science and Engineering Central South University of TechnologyChangsha 410083China

Nine functions of atomic volume interaction have been established. The values of average atomic volumes and lattice constants of ag-cu alloys obtained from each V-function are, respectively, equal to each other and in good agreement with experimental values. But the average atomic volumes of components and the volumes of characteristic atoms obtained from each V-function are different from each other. Only after the correlative study of energy, volume and electronic structure is carried out, can the V-function be correctly chosen, can a knowledge system about the alloys be established, thus providing the base for scientific design of new alloys. The relationships between lattice parameters of metastable phases of ag-cu alloys and composition and between average properties and partial molar properties of components are discussed.

关键词： ag-cu alloys atomic volume lattice constant partial molar property

Atomic energies and Gibbs energy functions of ag-cu alloys

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Science China(Technological Sciences) 1998年第2期41卷 146-156页

作者：谢佑卿 Department of Materials Science and Engineering Central South University of TechmolgyChangsha 410083China

The rationality of characteristic crystals model has been expounded. Nine new Gibbs energy functions of CC theory have been established. The regular solution model corresponds to the simplest situation of CC model. Any G-functions of CC theory can be used to represent liquid and fcc phases of ag-cu system. The lattice stability parameters of characteristic crystals for ag-cu alloys can be described with the form accepted by the SGTE group. Only when we have made studies on the law of change of energy, volume and electronic structure of the ag-cu system, can we choose the G-function correctly and then establish an integral knowledge system and the database, so as to lay a good foundation for the scientific design of new alloys.

关键词： ag-cu alloys Gibbs free energy heat of formation

Mechanisms of eutectic lamellar destabilization upon rapid solidification of an undercooled ag-39.9 at.% cu eutectic alloy

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Journal of Materials Science & Technology 2020年第24期59卷 173-179页

作者： H.Dong Y.Z.Chen Z.R.Zhang G.B.Shan W.X.Zhang F.Liu State Key Lab.of Solidification Processing Northwestern Polytechnical UniversityXi’an 710072China Yangtze River Delta Research Institute of NPU Taicang 215400China

The eutectic ag-cu alloys exhibiting fine ag-cu lamellar eutectic structure formed upon rapid solidification have great potentials being used in various engineering ***,the desired fine primary lamellar eutectic structure(PLES)is usually replaced by a coarse anomalous eutectic structure(AES)when the undercooling prior to solidification exceeds a certain *** forming mechanism of AES in the undercooled eutectic ag-cu alloy has been a controversial *** this work,the undercooled ag-39.9 at.% cu eutectic alloy is solidified under different cooling conditions by using techniques of melt fluxing and copper mold *** results show that the coupled eutectic growth of this alloy undergoes a transition from a slow eutectic-cellular growth(ECG)to a rapid eutectic-dendritic growth(EDG)above a undercooling of 72 K,accompanying with an abrupt change of the distribution and amount of AES in as-solidified *** kinds of primary lamellar eutectic structures are formed by ECG and EDG during recalescence,*** destabilization of PLES that causes the formation of AES is ascribed to two different mechanisms based on the microstructural examination and theoretical *** 72 K,the destabilization of PLES formed by slow ECG is caused by the mechanism of"termination migration"driven by interfacial *** above 72 K,the destabilization of PLES formed by rapid EDG is attributed to the unstable perturbation of interface driven by interfacial energy and solute supersaturation.

关键词： ag-cu alloys Rapid solidification Undercooling Eutectics Destabilization