School of Mechanical, Materials and Mechatronic Engineering
SEMINAR Influence of Grain Size on Plastic Auxeticity and Mechanical Properties of NiTi Alloy
PRESENTER Mr. Xiaohui Bian WHERE BLD 8.114 DATE Thursday, 7th of April 2016 TIME 12.30 -13.30
ABSTRACT Materials presenting a negative Poisson's ratio (auxetics) have drawn attention for the past two decades because of their unusual and sometimes extreme mechanical response, such as higher shear modulus, hardness value (indentation toughness), acoustic damping, vibration absorption, etc.. Unlike elastic auxetics which deform within limited strain range or those specially fabricated cellular solids, polymers, composites which are costly and less applicable for carrying stress, plastic auxetics undergo a bulk microstructural change during deformation through mechanisms such as deformation-induced twinning or crystallographically reversible phase transformation. NiTi alloys exhibit superelasticity (SE) that has been related to reversible phase transformation, suggesting a potential for intermetallic NiTi compound exhibiting plastic auxetic behaviour. In this presentation, a polycrystalline Ni-rich NiTi shape memory alloy (SMA) rod was subjected to different recrystallisation heat treatments to obtain grain size variation. Preliminary characterisation using dilatometry, hardness test, TEM, X-ray diffraction and electron backscatter diffraction was carried out for both as-received and annealed specimens. This provides the basis for mechanical behaviour studies and for the establishment of microstructure-property relationship. Future plan is discussed.
ABOUT THE SPEAKER
Mr. Xiaohui Bian is a PhD candidate at the University of Wollongong since January 2015. He received a Bachelor
s degree of Engineering at the Shandong University of Science and Technology and a Masters degree of Engineering at the University of Science and Technology Beijing, P. R. China. Xiaohui published one journal paper during his Master`s work. His research work is related to heat treatment, ex-situ/in-situ mechanical behaviour and microstructure characterisation.?
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