Microstructure and high strain rate superplasticity of in situ composite synthesised from aluminium and nano­ZrO2 particles by powder metallurgy

Author: Geng L.   Imai T.   Mao J.F.   Takagi M.   Yao C.K.  

Publisher: Maney Publishing

ISSN: 1743-2847

Source: Materials Science and Technology, Vol.17, Iss.2, 2001-02, pp. : 187-194

Disclaimer: Any content in publications that violate the sovereignty, the constitution or regulations of the PRC is not accepted or approved by CNPIEC.

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Abstract

Pure aluminium matrix composites reinforced mainly with a fine needle­like Al3Zr phase were synthesised by the reaction between nanocrystalline ZrO2 particles and pure aluminium using powder metallurgy followed by hot extrusion and hot rolling. After extrusion, the composite fabricated with 5 vol.-%ZrO2 had a strain rate sensitivity (m value) of 0.31 and a total elongation of 156% at 650°C and 1.3×10-1 s-1. The high strain rate superplasticity was improved by hot rolling. After hot rolling, the m value of the composite fabricated with 10%ZrO2 particles was 0.40 and the total elongation was 204% at 640°C and 1.3×10-1 s-1. The superplastic deformation mechanism for the present composites involves grain boundary sliding and interfacial sliding. From this mechanism, the following experimental results can be easily understood: the total elongation increased with temperature, and the strain rate at which maximum total elongation was attained increased with increasing deformation temperature.

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