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Study Data from Hong Kong University of Science and Technology Provide New Insights into Nanocrystals

May 30, 2014

By a News Reporter-Staff News Editor at Science Letter -- Current study results on Nanocrystals have been published. According to news reporting originating from Hong Kong, People's Republic of China, by NewsRx correspondents, research stated, "We report recent advances in the experimental and theoretical study of grain size (GS) effects on the thermal and mechanical properties of nanostructured NiTi polycrystalline shape memory alloy (SMA). It is shown that when GS < 60 nm, the superelastic stress-strain hysteresis loop area (H) of the polycrystal decreases rapidly with GS and tends to vanish as GS approaches 10 nanometers."

Our news editors obtained a quote from the research from the Hong Kong University of Science and Technology, "At the same time, the temperature dependence of the transition stress also decreases with GS and eventually approaches zero, leading to a wide superelastic temperature window and breakdown of the Clausius-Claperyon relationship. Rate dependence of the stress-strain responses is significantly reduced and the cyclic stability of the material is improved by the nanocrystallization. It is proposed that the emergence of such significant changes in the behavior of the material with GS reduction originate from the large increase in the area-to-volume ratios of the nanometer-thick interfaces (grain boundary and Austenite-Martensite (A-M) interface) in the polycrystal. In particular, with GS reduction, interfacial energy terms will gradually become dominant over the bulk energy of the crystallite, eventually bring fundamental changes in the phase transition responses of the material."

According to the news editors, the research concluded: "Modelling strategy leading to the establishment of quantitative relationships among GS, grain boundary, A-M interfaces and the macroscopic responses of the material are outlined."

For more information on this research see: Effects of grain size on phase transition behavior of nanocrystalline shape memory alloys. Science China-Technological Sciences, 2014;57(4):671-679. Science China-Technological Sciences can be contacted at: Science Press, 16 Donghuangchenggen North St, Beijing 100717, Peoples R China (see also Nanocrystals).

The news editors report that additional information may be obtained by contacting Q.P. Sun, Hong Kong University of Science & Technology, Dept. of Mech & Aerosp Engn, Hong Kong 999077, Hong Kong, People's Republic of China. Additional authors for this research include A. Aslan, M.P. Li and M.X. Chen.

Keywords for this news article include: Asia, Alloys, Hong Kong, Nanotechnology, Nanocrystalline, Emerging Technologies, People's Republic of China

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Source: Science Letter

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