In the scope of the present study, Ni-rich TiNi (Ti-50.6 at %Ni) foams with porosities in the range 38-59% were produced by space holder technique using spherical magnesium powders as space formers. Single phase porous TiNi alloys produced with spherical pores were subjected to loading-unloading cycles in compression up to 250 MPa stress levels at different temperatures in as-processed and aged conditions. It has been observed that strength, elastic modulus and critical stress for inducing martensite decrease with increasing porosity. Partial superelasticity was observed for all porosity levels at different test temperatures and conditions employed. Irrecoverable strain was found to decrease with pre-straining and with increasing test temperature. Unlike in bulk TiNi alloys a constant stress plateau has not been observed during the compression testing of porous TiNi alloys. Instead linear superelasticity with a quite steep slope allowing 5% applied strain to be recovered after pre-straining or aging was observed. Even at test temperatures higher than austenite finish temperature in as-sintered and aged condition, strain applied could not be recovered fully due to martensite stabilization resulting from heavy deformation of macro-pore walls and sintering necks. TiNi foams produced with porosities in the range of 38-51% meet the main requirements of biomaterials in terms of mechanical properties for use as bone implant.
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http://dx.doi.org/10.1016/j.jmbbm.2012.05.018 | DOI Listing |
Materials (Basel)
December 2024
School of Materials Science and Engineering, Shanghai University of Engineering Science, Shanghai 201620, China.
Ti6Al4V/Inconel 718 composites were prepared using arc additive manufacturing technology at different deposition currents. The properties of the composites directly influence the performance of the gradient materials, while heat input further affects the composites' properties. The results indicate that at a deposition current of 35 A, Ti elements diffuse into the Inconel 718 alloy.
View Article and Find Full Text PDFMolecules
September 2024
Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093, China.
To meet the demands for high-temperature performance and lightweight materials in aerospace engineering, the Au-Ni solder is often utilized for joining dissimilar materials, such as TiAl-based alloys and Ni-based high-temperature alloys. However, the interaction between Ti and Ni can lead to the formation of brittle phases, like TiNi, TiNi, and TiNi, which diminish the mechanical properties of the joint and increase the risk of crack formation during the welding process. Cu doping has been shown to enhance the mechanical properties and high-temperature stability of the Au-Ni brazed joint's central area.
View Article and Find Full Text PDFACS Biomater Sci Eng
October 2024
School of Nuclear Science and Technology, University of Science and Technology of China, Hefei, Anhui 230026, China.
With the accelerating trend of global aging, bone damage caused by orthopedic diseases, such as osteoporosis and fractures, has become a shared international event. Traffic accidents, high-altitude falls, and other incidents are increasing daily, and the demand for bone implant treatment is also growing. Although extensive research has been conducted in the past decade to develop medical implants for bone regeneration and healing of body tissues, due to their low biocompatibility, weak bone integration ability, and high postoperative infection rates, pure titanium alloys, such as Ti-6A1-4V and Ti-6A1-7Nb, although widely used in clinical practice, have poor induction of phosphate deposition and wear resistance, and Ti-Zr alloy exhibits a lack of mechanical stability and processing complexity.
View Article and Find Full Text PDFChem Asian J
July 2024
Institute of Materials Research and Engineering, ACI, SINGAPORE.
The development of new thermoelectric conversion and cooling materials is an important means of addressing global climate and heat emissions in the future. While heavy and toxic elements like tellurium and lead are traditionally used to make thermoelectric materials with poor mechanical properties, recent decades have seen a gradual push towards greener and more sustainable alternatives. One such potential alternative material for thermoelectric and thermal management applications would be the Nitinol (TiNi) shape memory alloy, due to their superior mechanical properties.
View Article and Find Full Text PDFMaterials (Basel)
May 2024
School of Mechanical Engineering, Xi'an Jiaotong University, Xi'an 710049, China.
To explore a new method to improve the wear resistance of TiNi shape memory alloy (SMA), Ti-50.8Ni alloy was treated by the method of ultrasonic surface shot peening. The microstructure evolution, hardness, and tribological behaviors have been further investigated to evaluate the effect of ultrasonic surface shot peening (USSP).
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