High damping capacity in porous NiTi alloy with bimodal pore architecture

• Published in: Journal of alloys and compounds Vol. 550; pp. 297 - 301
• Main Authors: Zhang, X.X., Hou, H.W., Wei, L.S., Chen, Z.X., Wei, W.T., Geng, L.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 15.02.2013; Elsevier
• Subjects: Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Damping; Elasticity, elastic constants; Exact sciences and technology; Foams; Intermetallics; Martensite transformation; Martensitic transformations; Materials science; Mechanical and acoustical properties of condensed matter; Mechanical properties of solids; Nickel base alloys; Nickel compounds; Nickel titanides; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Physics; Porosity; Porous alloy; Powder metallurgy; Shape memory alloys; TiNi shape memory alloy; Titanium compounds; Damping; TiNi shape memory alloy; Martensite transformation; Powder metallurgy; Porous alloy; Dislocation motion; Densification; Nickel alloys; Phase transformations; Porous materials; Martensitic transformations; Heat treatments; Shape memory effects; Titanium alloys; Dual phase structure; Shape memory alloy; Superelasticity; Sintering; Porosity; Bulk modulus
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2012.09.145

[Display omitted] ► We prepared porous NiTi alloy with pressureless sintering Ni/Ti powders with NaCl space holder. ► The pore architecture of this porous Ni50.5Ti49.5 alloy with large and small pores was investigated. ► This unique bimodal pore architecture contributed to the high damping capacity of the foam. ► The low modulus and pore size met the demand of cancellous bones. Porous NiTi exhibits pseudoelasticity, shape memory and low modulus, and thus shows application potential as high damping and bio-materials. Here Ni50.5Ti49.5 foam with bimodal pore structure was prepared by elemental powder sintering and high damping capacity demonstrated. NaCl particles of 500–600μm and 75–90μm diameters were adopted as space holder to create large and small pores with porosity of 40%. Incomplete densification of NiTi alloy created even smaller pores of 10–50μm and contributed another 21.47% porosity. This NiTi foam containing bimodal pores has a compressive modulus of 1.83GPa, smaller than that of foam with single pores or estimation by Gibson–Ashby model. This low modulus is attributed to the stress-induced martensite transformation under compressive load. The foam exhibits high damping capacities during phase transformation and at austenite region because of deformation, dislocation motion in thin nodes/walls and stress-induced martensite formation.