Modeling of shear induced coarsening effects in semi-solid alloys  

作　　者：M.MODIGEL L A.POLA 

机构地区：[1]AVT,Chair of Mechanical Process Engineering,RWTH Aachen University [2]Dipartimento di Ingegneria Meccanica e Industriale,Uni.degli Studi di Brescia

出　　处：《Transactions of Nonferrous Metals Society of China》2010年第9期1696-1701,共6页中国有色金属学报（英文版）

摘　　要：In long-term rheological shear experiments with semi-solid alloys, coarsening of the particles will falsify the interpretation of the experimental results.The coarsening is intensified by the shear induced convection and the mean size of the particles is changed significantly during the experiments.A simple model has been set up which takes the influence of the convection into account.The resulting growth law has been simplified for diffusion and convection dominated growth.The growth law was verified with shear experiments in a Searl-rheometer with A356 and tin-lead alloys.The experiments demonstrated that under convection the growth follows a linear time law and that the rate constant depends on the root of the shear rate.The correction of experimental results to gain the true viscosity function is demonstrated for a shear jump experiment with A356.In long-term rheological shear experiments with semi-solid alloys, coarsening of the particles will falsify the interpretation of the experimental results. The coarsening is intensified by the shear induced convection and the mean size of the particles is changed significantly during the experiments. A simple model has been set up which takes the influence of the convection into account. The resulting growth law has been simplified for diffusion and convection dominated growth. The growth law was verified with shear experiments in a Searl-rheometer with A356 and tin-lead alloys. The experiments demonstrated that under convection the growth follows a linear time law and that the rate constant depends on the root of the shear rate. The correction of experimental results to gain the true viscosity function is demonstrated for a shear jump experiment with A356.

关 键 词：MICROSTRUCTURE COARSENING Ostwald ripening flow function VISCOSITY RHEOLOGY semi-solid alloys 

分 类 号：TG249[金属学及工艺—铸造]