Study of comparative effectiveness of thermally stable nanoparticles on high temperature deformability of wrought AZ31 a
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Muralidharan Paramsothy Department of Mechanical Engineering, National University of Singapore, Singapore 117576, Singapore
Bekir Sami Yilbas Department of Mechanical Engineering, King Fahd University of Petroleum & Minerals, Dhahran 31261, Kingdom of Saudi Arabia
Manoj Gupta Department of Mechanical Engineering, National University of Singapore, Singapore 117576, Singapore (Received 4 March 2014; accepted 8 May 2014)
Thermally stable nanosized Al2O3 particles and carbon nanotubes (CNTs) are comparatively effective in simultaneous improvement of strength and ductility of wrought magnesium alloy AZ31 when incorporated in microstructure. Understanding the comparative effectiveness of these nanosized reinforcements on the high temperature deformation process of wrought AZ31 alloy is important for its potential wider automotive body application. The current study has revealed that both reinforcements are competitively effective in inducing matrix grain and intermetallic particles refinement and strengthening almost to a theoretically predicted value. Although high temperature flow stress of AZ31 was found to closely match due to incorporation of both of the nanosized reinforcements, alumina was more efficient in improving the failure strain of matrix alloy. Addition of remarkably a small amount of nanosized alumina particles or CNTs introduced huge potential in near net shape formability of AZ31 alloy at a temperature much below than the widely used 350 °C. Among the two reinforcements used in this study, alumina was found to be more efficient when compared to the effect of CNTs.
I. INTRODUCTION
Address all correspondence to this author. e-mail: [email protected], itsforfi[email protected] DOI: 10.1557/jmr.2014.112
temperature. Among the wrought magnesium alloys, AZ31 has high potential for wider automotive body application due to relatively competitive combination of strength and ductility compared with other commercially available Mg–Al–Zn ternary alloys. However, the broader application of this alloy as an ideal and competitive substitute requires overcoming these challenges including improvement in toughness, high temperature deformability, and corrosion resistance. The requirement for the significantly high temperature (nearly 0.67 Tm (K)) in hot work for magnesium alloys is mainly due to the presence of brittle intermetallics and formation of twin under stress instead of basal or prismatic slip.1,2 The nearly ideal c/a ratio of the hexagonally close-packed crystal structure is believed to be the promoter of the deformation twin in magnesium microstructure. Quest in recent years has led to significant improvements in ambient temperature toughness of the AZ31 alloy with nanosized nonmetallic reinforcements, namely, alumina and carbon nanotubes (CNTs)10,11 with potential induction of extra slip system.12 Among these nanosized reinforcements, alumina effectively reduced flow stress required for high temperature deformation of AZ31 alloy.13 The presence of nanosized
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Ó Materials Research Society 2014
Magnesium al
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