Modeling of microstructure evolution of AZ80 magnesium alloy during hot working process using a unified internal state variable method

In this paper, a unified internal state variable(ISV) model for predicting microstructure evolution during hot working process of AZ80 magnesium alloy was developed. A novel aspect of the proposed model is that the interactive effects of material hardening, recovery and dynamic recrystallization(DRX) on the characteristic deformation behavior were considered by incorporating the evolution laws of viscoplastic flow, dislocation activities, DRX nucleation and boundary migration in a coupled manner. The model parameters were calibrated based on the experimental data analysis and genetic algorithm(GA) based objective optimization. The predicted flow stress, DRX fraction and average grain size match well with experimental results. The proposed model was embedded in the finite element(FE) software DEFORM-3 D via user defined subroutine to simulate the hot compression and equal channel angular extrusion(ECAE) processes. The heterogeneous microstructure distributions at different deformation zones and the dislocation density evolution with competitive deformation mechanisms were captured.This study can provide a theoretical solution for the hot working problems of magnesium alloy.

MY WORK ON THE EPICENTRAL PROCESS OF EARTHQUAKES

In 1962, I graduated from the faculty of geophysics of Beijing University and was admitted to a postgraduate program at the CAS Institute of Geophysics after an entrance examination in the same year. During the past 30 years, I have been invariabl.y engaged in theoretic and applied research of the seismic wave and its epicenter.Since the early 1970s, my work has shifted to the epicentral process, applying research results to abstracting epicentral information from seismic wave data, "zero fre-

MY WORK FOR UPDATING PETROCHEMICAL CATALYSIS AND PROCESSING

After graduating from Zhejiang University in 1952, I came to work at the Institute of Petroleum Processing (which was renamed the Dalian Institute of Chemical Physics in 1959) under the CAS in Dalian City and served as a research chemist there. In the 1950s,my research interest was mainly concentrated on synthetic liquid fuels. After the discovery of a large oilfield in the Daqing area in 1960, a great impetus was brought to the

On Clausius’, Post-Clausius’, and Negentropic Thermodynamics

The evidence here provided shows that the thermodynamics of the second law, as currently understood, originated in a correction of the flaws affecting Clausius original work on this matter. The body of knowledge emerging from this correction has been here called post-Clausius’ thermodynamics. The said corrections, carried on with the intended goal of preserving the validity of Clausius’ main result, namely the law of increasing entropy, made use of a number of counterintuitive or logically at fault notions. A joint revision of Clausius’ and post-Clausius’ work on the second law, carried on retaining some of Clausius original notions, and disregarding others introduced by post-Clausius thermodynamics, led this author to results in direct contradiction to the law of increasing entropy. Among the key results coming out of this work we find the one stating that the total-entropy change for spontaneous thermodynamic processes is the result of the summation of the opposite-sign contributions coming from the entropic (energy degrading) and negentropic (energy upgrading) changes subsumed by any such process. These results also show, via the total-entropy change for a non-reversible heat engine, that negentropic thermodynamics subsumes post-Clausius thermodynamics as a special case.