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Fabrication of porous NiTi shape memory alloy structures using laser engineered net shaping
Author(s) -
Krishna B. Vamsi,
Bose Susmita,
Bandyopadhyay Amit
Publication year - 2009
Publication title -
journal of biomedical materials research part b: applied biomaterials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.665
H-Index - 108
eISSN - 1552-4981
pISSN - 1552-4973
DOI - 10.1002/jbm.b.31238
Subject(s) - materials science , porosity , nickel titanium , shape memory alloy , composite material , pseudoelasticity , alloy , volume fraction , biomaterial , elastic modulus , titanium alloy , metallurgy , microstructure , martensite , nanotechnology
Porous NiTi alloy samples were fabricated with 12–36% porosity from equiatomic NiTi alloy powder using laser engineered net shaping (LENS™). The effects of processing parameters on density and properties of laser‐processed NiTi alloy samples were investigated. It was found that the density increased rapidly with increasing the specific energy input up to 50 J/mm 3 . Further increase in the energy input had small effect on density. High cooling rates associated with LENS processing resulted in higher amount of cubic B2 phase, and increased the reverse transformation temperatures of porous NiTi samples due to thermally induced stresses and defects. Transformation temperatures were found to be independent of pore volume, though higher pore volume in the samples decreased the maximum recoverable strain from 6% to 4%. Porous NiTi alloy samples with 12–36% porosity exhibited low Young's modulus between 2 and 18 GPa as well as high compressive strength and recoverable strain. Because of high open pore volume between 36% and 62% of total volume fraction porosity, these porous NiTi alloy samples can potentially accelerate the healing process and improve biological fixation when implanted in vivo . Thus porous NiTi is a promising biomaterial for hard tissue replacements. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009