RELATIONSHIP BETWEEN THE INITIAL GRAIN BOUNDARY ENERGY OF A MATERIALAND ITS WORK HARDENING ESPONSES
When the grain size of a material becomes very small,such as in the sub-micro-and nano-meter range,plastic deformation responses of the material demonstrate a number of special features,such as high hardening rate at the onset of plastic deformation,low hardening rate at high strain levels and early appearance of shear bands.To understand these behaviours,the necessity for grain size grading has been recognized to be important,although the nature of such classification is still unclear.The traditional dislocation theories dealing with the shift of these stages provide insufficient insight on such grain size effect.In the present work,a critical grain size criterion for the shifting of deformation mechanisms is proposed.This extended model relates the grain boundary energy density to the critical energy triggering such transitions,and permits,for the first time,a quantitative grading of grain size.It isfound that the predictions made with this model on ultrafme-and nano-twinned copper showed a very good agreement with experimental results.Thus,the effects of grain size in plastic deformation mechanism are now generalized.
Zhirui Wang
Department of Materials Science and Engineering,University of Toronto,184 College Street,Toronto,Ontario,Canada,MSS 3E4
国际会议
第二届国际非均质材料力学会议(The Second International Conference on Heterogeneous Material Mechanics)
安徽黄山
英文
153
2008-06-03（万方平台首次上网日期，不代表论文的发表时间）