Evolution of Thermoplastic Shear Localization and Related Microstructures in Al/SiC_p Composites Under Dynamic Compression  

作　　者：YongboXU ZhongLING 等 

机构地区：[1]ShenyangNationalLaboatoryandMaterialsScience,InstituteofMetalResearch,ChineseAcademyofSciences,Shenyang110016,China [2]LaboratoryforNon-LinearMechanicsofContinuousMedia,InstituteofMe

出　　处：《Journal of Materials Science & Technology》2002年第6期504-508,共5页材料科学技术（英文版）

基　　金：This work was supported by the National Natural Science Foundation of China. (No. 59971059)

摘　　要：The localized shear deformation in the 2024 and 2124 Al matrix composites reinforced with SiC particles was investigated with a split Hopkinson pressure bar (SHPB) at a strain rate of about 2.0×103 s-1. The results showed that the occurrence of localized shear deformation is sensitive to the size of SiC particles. It was found that the critical strain, at which the shear localization occurs, strongly depends on the size and volume fraction of SiC particles. The smaller the particle size, the lower the critical strain required for the shear localization. TEM examinations revealed that Al/SiCp interfaces are the main sources of dislocations. The dislocation density near the interface was found to be high and it decreases with the distance from the particles. The Al matrix in shear bands was highly deformed and severely elongated at low angle boundaries. The AI/SiCp interfaces, particularly the sharp corners of SiC particles, provide the sites for microcrack initiation. Eventual fracture is caused by the growth and coalescence of microcracks along the shear bands. It is proposed that the distortion free equiaxed grains with low dislocation density observed in the center of shear band result from recrystallization during dynamic deformation.The localized shear deformation in the 2024 and 2124 Al matrix composites reinforced with SiC particles was investigated with a split Hopkinson pressure bar (SHPB) at a strain rate of about 2.0×103 s-1. The results showed that the occurrence of localized shear deformation is sensitive to the size of SiC particles. It was found that the critical strain, at which the shear localization occurs, strongly depends on the size and volume fraction of SiC particles. The smaller the particle size, the lower the critical strain required for the shear localization. TEM examinations revealed that Al/SiCp interfaces are the main sources of dislocations. The dislocation density near the interface was found to be high and it decreases with the distance from the particles. The Al matrix in shear bands was highly deformed and severely elongated at low angle boundaries. The AI/SiCp interfaces, particularly the sharp corners of SiC particles, provide the sites for microcrack initiation. Eventual fracture is caused by the growth and coalescence of microcracks along the shear bands. It is proposed that the distortion free equiaxed grains with low dislocation density observed in the center of shear band result from recrystallization during dynamic deformation.

关 键 词：Al/SiCp composites Shear localization RECRYSTALLIZATION Dislocations 

分 类 号：TB333[一般工业技术—材料科学与工程]