Authors: Zhi Fang Zhengyi Jiang Xiaogang Wang Cunlong Zhou Dongbin Wei Xianghua Liu
Publish Date: 2015/03/12
Volume: 79, Issue: 9-12, Pages: 1905-1914
Abstract
Size effects play a significant role in microforming process and any dimensional change can have a great impact on materials’ mechanical properties In this paper the size effects on deformation behaviour and fracture of phosphor foil were investigated in the form of grain size effect the ratio of materials’ thickness T to average grain size D by micro tensile tests The ratio was designed to be closed to but larger than less than and equal to 1 respectively The results show that the amount of plastic deformation decreases with the decrease of the ratio of T/D which indicates that the grain size plays a significant role and grain deformation modes differ when the ratio changes It is also found that their fractograph reflects different features in terms of microdimples and cleavage planes further demonstrating that when T/D 1 its materials have a tendency to fracture ductilely while materials would like to conduct brittle fracture when T/D 1 So the ratio of T/D which is close to 1 can be regarded as the divide of ductile fracture and brittle fracture For T/D 1 a new constitutive model is proposed based on the classic composite model The model’s results are compared with the experimental ones and the efficiency of the developed models is verified
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