Discrete dislocation plasticity analysis of the high-temperature cyclic response of composites

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:712

Article

Shishvan, Siamak S.^1,2  McMeeking, Robert M.^3,4,5  Pollock, Tresa M.³  Deshpande, Vikram S.² 

[1] Univ Tabriz, Dept Struct Engn, POB 51666-16471, Tabriz, Iran

[2] Univ Cambridge, Dept Engn, Trumpington St, Cambridge CB2 1PZ, England

[3] Univ Calif Santa Barbara, Dept Mat, Santa Barbara, CA 93106 USA

[4] Univ Calif Santa Barbara, Dept Mech Engn, Santa Barbara, CA 93106 USA

[5] Univ Aberdeen, Kings Coll, Sch Engn, Aberdeen AB24 3UE, Scotland

关键词: High-temperature composite;    Cyclic loading;    Interfacial diffusion;    Discrete dislocation plasticity;    Size effects;   

DOI  :  10.1016/j.msea.2017.12.034

来源: Elsevier

【 摘 要 】

Discrete dislocation plasticity (DDP) analysis of the high-temperature cyclic deformation of two-phase composites comprising a plastic matrix and elastic precipitates is presented. Deformation of the matrix is by climb assisted glide of dislocations while the precipitates deform by a combination of bulk elasticity and stress-driven interfacial diffusion. The DDP calculations predict a cyclically softening response due to the formation of dislocation cell structures within the matrix. The dislocation cell sizes decrease with decreasing size of the unit cell (or equivalently matrix channels) and this results in an increased cyclic softening rate in composites with smaller unit cells. Interfacial diffusion also enhances the formation of dislocation cell structures and thereby promotes cyclic softening. These results are consistent with predictions of the creep behaviour that indicate that the increase in the creep rate (i.e. tertiary creep) is also associated with the formation of dislocation cell structures within the matrix.

【 授权许可】

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