利用Pandat相平衡热力学计算软件优化和计算了Ir-Pt二元相图。采用SGTE(Science Group Thermodata Europe)数据库中的表达式描述纯组元(Ir和Pt)的Gibbs自由能,采用固溶体相热力学模型描述Ir-Pt二元体系中的液相和固溶体相。利用Pandat中的PanOptimizer优化平台,并结合最新的相关数据,对Ir-Pt二元体系中各相的参数进行了优化,优化得到了Ir-Pt二元体系中各相的热力学参数。利用优化的热力学参数对Ir-Pt二元合金相图进行了计算,计算得到的相图表明调幅分解的临界点为995℃、50%Ir(摩尔分数)左右,与SGTE贵金属合金数据库所提出的Ir-Pt二元体系在相图和热力学数据上都较为吻合。
The grain statistics effect was investigated through asymmetric rolling of pure copper foil by a realistic polycrystalline aggregates model and crystal plasticity element finite model.A polycrystalline aggregate model was generated and a crystal plasticity-based finite element model was developed for each grain and the specimen as a whole.The crystal plasticity model itself is rate dependent and accounts for local dissipative hardening effects and the original orientation of each grain was generated based on the orientation distribution function（ODF）.The deformation behaviors,including inhomogeneous material flow,decrease of contact press and roll force with the increase of grain size for the constant size of specimens,were studied.It is revealed that when the specimens are composed of only a few grains across thickness,the grains with different sizes,shapes and orientations are unevenly distributed in the specimen and each grain plays a significant role in micro-scale plastic deformation and leads to inhomogeneous deformation and the scatter of experimental and simulation results.The slip system activity was examined and the predicted results are consistent with the surface layer model.The slip band is strictly influenced by the misorientation of neighbor grain with consideration of slip system activity.Furthermore,it is found that the decrease of roll force and the most active of slip system in surface grains are caused by the increase of free surface grain effect when the grain size is increased.The results of the physical experiment and simulation provide a basic understanding of micro-scaled plastic deformation behavior in asymmetric foil rolling.
Based on the research on the solidification of twin-roll continuous casting aluminum thin strip, the analytical model of heterogeneous nucleation, the growth kinetics of tip （KGT） and columnar dendrite transformation to equiaxed dendrite （CET） of twin-roll continuous casting aluminum thin strip solidification was established by means of the principle of metal solidification and modem computer emulational technology. Meantime, based on the cellular automaton, the emulational model of twin-roll continuous casting aluminum thin strip, solidification was established. The foundation for the emulational simulation of twin-roll casting thin strip solidification structure was laid. Meanwhile, the mathematical simulation feasibility was confirmed by using the solidification process of twin-roll continuous casting aluminum thin strip.
