Producing Bulk Ultrafine-Grained Materials by Severe Plastic Deformation, etc.No Access

EVOLUTION OF NANO GRAINS IN A BULKY Cu-Zn ALLOY ENHANCED BY MECHANICAL TWINNING DURING MULTI-DIRECTIONAL FORGING

Department of Mechanical Engineering and Intelligent Systems, UEC Tokyo (The University of Electro-Communications), Chofu, Tokyo 182-8585, Japan

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Y. NAKAO

Department of Mechanical Engineering and Intelligent Systems, UEC Tokyo (The University of Electro-Communications), Chofu, Tokyo 182-8585, Japan

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, and

T. SAKAI

Department of Mechanical Engineering and Intelligent Systems, UEC Tokyo (The University of Electro-Communications), Chofu, Tokyo 182-8585, Japan

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https://doi.org/10.1142/S0217979208047614Cited by:2 (Source: Crossref)

Abstract

A bulky Cu-Zn alloy was multi-directionally forged (MDFed) at 77 K and 300 K up to a cumulative strain of 6.0 at maximum. With increasing strain, the evolved substructure changed gradually to uniform ultra fine grains. The tendency of the microstructural evolution and its mechanism depended strongly on the MDF temperature. Mechanical twins accelerated the finer grain fragmentation by subdivision of the grains and by intersection of the twins themselves due to MDF. Twinning appeared more frequently and uniformly at 77 K than at 300 K. The average grain size obtained at a cumulative strain of 6.0 was about 17 nm at 77 K and 26 nm at 300 K. The evolution of the microstructure accompanied by mechanical twinning is precisely investigated.

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