Study on Preparation of Gradient Porous NiTi Alloys by Powder Metallurgy Method

2011 ◽  
Vol 299-300 ◽  
pp. 671-674
Author(s):  
Qiang Li ◽  
Jing Yuan Yu ◽  
Guo Chao Qi
Keyword(s):  
Phase Composition ◽  
Elastic Modulus ◽  
Powder Metallurgy ◽  
Porous Materials ◽  
Niti Alloy ◽  
Powder Metallurgy Method ◽  
Compressive Properties ◽  
Niti Alloys ◽  
Porous Niti ◽  
Tini Phase

Gradient porous NiTi alloys were fabricated by powder metallurgy method using NH4HCO3as space-holder. The effect of content and distribution of NH4HCO3on pore characteristic, phase composition and compressive properties was studied. The results showed the content of TiNi phase increased with the decrease of the content of NH4HCO3. When the distribution of NH4HCO3varying form 12wt%-12wt%-12wt% to 12wt%-6wt%-12wt% and 12wt%-0wt%-12wt%, the stress and elastic modulus of porous NiTi alloys increased from 228MPa to 321MP and 446MPa, from 4.8GPa to 5.6GPa and 6.8GPa, respectively. Compared with uniform porous materials, gradient porous NiTi alloy exhibited better superelasticity.

Study on Effect of Sintering Temperature on Microstructure and Compressive Property of Porous NiTi Alloys

2011 ◽  
Vol 299-300 ◽  
pp. 480-483 ◽  
Author(s):  
Jing Yuan Yu ◽  
Qiang Li
Keyword(s):  
Compressive Strength ◽  
Phase Composition ◽  
Sintering Temperature ◽  
Testing Machine ◽  
Compressive Property ◽  
Powder Metallurgy Method ◽  
Niti Alloys ◽  
Porous Niti ◽  
Universal Testing ◽  
Niti Phase

Porous NiTi alloys were prepared by powder metallurgy method using NH4HCO3as space-holder. The effect of sintering temperature on pore characteristic, phase composition and compressive property of porous NiTi alloys was studied by XRD, SEM, EDS and a universal testing machine. The results show with the increase of sintering temperature the porosity of porous NiTi alloys first increases and then decreases, but the content of NiTi phase, compressive strength and modulous of sintered products continuously increase. When sintered at 980°C for 2h, the porous NiTi alloys have higher porosity of 53.6%, better compressive strength of 173.7MPa and elastic modulous of 4.2GPa. The phases of sinter products are mainly composed by TiNi, Ti2Ni, and TiNi3phases.

Study on Preparation and Anodic Oxidation of Gradient Porous NiTi Alloy

2012 ◽  
Vol 430-432 ◽  
pp. 1373-1377
Author(s):  
Qiang Li ◽  
Jing Yuan Yu ◽  
Xu Dong Sun
Keyword(s):  
Anodic Oxidation ◽  
Niti Alloy ◽  
Surface Film ◽  
Powder Metallurgy Method ◽  
Release Behavior ◽  
Ion Release ◽  
Gradient Distribution ◽  
Niti Alloys ◽  
Porous Niti ◽  
Oxidation Technology

Gradient porous NiTi alloys were prepared by powder metallurgy method using NH4HCO3 as space-holder and modified by direct current-pulse anodic oxidation technology in low temperature. Pore characteristic and phase composition of gradient porous NiTi alloys were studied. Microstructure, composition, anti-corrosion and Ni ion release behavior of surface film were observed. The results show the porosity of porous NiTi alloys decreases from 53.2% to 42.8%, when the content of NH4HCO3 varying from uniformity to gradient distribution. The sintered gradient porous NiTi alloys composes with TiNi, Ti2Ni and TiNi3 phases. After anodic oxidation, Ti oxidation film with the thick of 240nm was formed on the gradient porous NiTi alloy. The corrosion resistance of gradient porous NiTi alloy was obviously improved and the rate of Ni release was significantly reduced.

Characteristics and compressive properties of porous NiTi alloy synthesized by SHS technique

2009 ◽  
Vol 515 (1-2) ◽  
pp. 93-97 ◽  
Author(s):  
Sirikul Wisutmethangoon ◽  
Nipon Denmud ◽  
Lek Sikong
Keyword(s):  
Niti Alloy ◽  
Compressive Properties ◽  
Porous Niti

Local Graded Structure in 6.5wt%Si-Fe Alloy and the Effect on Ductility

2005 ◽  
Vol 492-493 ◽  
pp. 59-62 ◽  
Author(s):  
Qiang Shen ◽  
Ran Li ◽  
Lian Meng Zhang
Keyword(s):  
Phase Composition ◽  
Powder Metallurgy ◽  
Deformation Behavior ◽  
Powder Metallurgy Method ◽  
Silicon Phase ◽  
Silicon Iron ◽  
Graded Structure ◽  
Composition And Structure ◽  
High Silicon ◽  
Si Content

The changes of phase composition and structure evolvement of Fe and Si powders with the ratio of 6.5wt%Si to 93.5wt%Fe were mainly studied. It is found that, the local graded structure, Fe-Fe(Si)-Fe3Si-(FeSi)-Si, forms due to the obvious diffusion and the alloying reaction between Fe and Si powders when sintering at 900-975oC. The graded structure, in which the high silicon phase based on Fe-Si alloys is packed by the low silicon solution based on Fe, exhibits a graded concentration of Si distribution. And most of the Fe-containing phase remains a state of lower Si content, less than that of 3wt%Si-Fe alloy, thus provides the good deformation behavior of rolling and cutting for the compacts. Therefore, it is feasible for the high silicon iron sheets to be produced by the powder metallurgy method.

Fabrication of Porous NiTi Alloy Using Organic Binders

2018 ◽  
pp. 38-62
Author(s):  
Neeraj Sharma ◽  
Kamal Kumar
Keyword(s):  
Powder Metallurgy ◽  
Young’S Modulus ◽  
Process Parameters ◽  
Mechanical Treatment ◽  
Young's Modulus ◽  
Niti Alloy ◽  
Compaction Pressure ◽  
Porous Niti ◽  
Organic Particles ◽  
Bio Compatibility

Nitinol has growing applications in aerospace industries, MEMS, and bio-medical industries due to its unique properties of pseudo-elasticity, bio-compatibility, and shape-memory effect. Behaviour of NiTi alloy can be changed by altering the composition, modifying the porosity, and applying external thermal and mechanical treatment. In this chapter, porous NiTi alloy with powder metallurgy is fabricated by varying the composition of polypropylene as an organic binder from 0% to 15%, and Young's modulus and porosity of porous alloy has been evaluated. The effect of process parameters—compaction pressure, sintering temperature, and sintering time—are evaluated using Taguchi L16 orthogonal array. These particles initially act as a binder but with the increase of temperature, the organic particles evaporate and create pores. With the increase of organic particle percentage, the porosity increases while Young's modulus decreases. SEM was used to characterize the fabricated porous NiTi alloy.

Study on Characteristic and Compressive Property of Porous NiTi Alloys Fabricated by Thermal Explosion Method

2010 ◽  
Vol 160-162 ◽  
pp. 644-649 ◽  
Author(s):  
Qiang Li ◽  
Jing Yuan Yu ◽  
Xu Dong Sun
Keyword(s):  
Particle Size ◽  
Phase Composition ◽  
Heating Rate ◽  
Thermal Explosion ◽  
Compressive Property ◽  
Porous Niti ◽  
Ni Powder ◽  
Explosion Method ◽  
Tini Phase ◽  
Niti Shape Memory Alloys

Porous NiTi shape memory alloys were fabricated by thermal explosion method using different Ti and Ni powder as initial materials. The effect of process parameters including heating rate, and particle size of Ti on pore characteristic and phase composition was analyzed. Microstructure, phase composition, and mechanical properties were studied by SEM, XRD, and compression test, respectively. The mechanism of thermal explosion reaction was studied. The results show higher heating rate and smaller Ti particle size result in higher porosity and bigger pores. The thermal explosion reaction starts with the melting of a eutectic between β-Ti(Ni) and Ti2Ni and the main phases of as-reacted products are TiNi phase which are the desired phases. NiTi2 and TiNi3 phases are also present in small amounts. The content of TiNi phase increases with increasing heating rate or decreasing Ti particle size. The compressive strength and Young’s modulus of compacts decrease with the increase of the porosity.

Biodegradable Behaviors of Mg-6%Zn-5%Hydroxyapatite Biomaterial

2011 ◽  
Vol 239-242 ◽  
pp. 1287-1291 ◽  
Author(s):  
Jun Zhao ◽  
Zhi Ming Yu ◽  
Kun Yu ◽  
Liang Jian Chen
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Powder Metallurgy ◽  
Simulated Body Fluid ◽  
Body Fluid ◽  
Corrosion Products ◽  
Powder Metallurgy Method ◽  
Corrosion Rates ◽  
Immersion Corrosion ◽  
Zn Alloy

The Mg-6%Zn-5%Hydroxyapatite (HA) biomaterial had been prepared through powder metallurgy method in this investigation. The mechanical properties and biodegradable behaviors of the Mg-Zn-HAcomposite in simulated body fluid were studied. The Mg-Zn-HA specimens obtained appropriate density, adjustable elastic modulus and compatible strength to natural bones. Immersion corrosion experiments revealed that 5wt% addition of HA in Mg-6%Zn alloy exhibited acceptable corrosion rates in simulated body fluid. The Mg matrix, Mg7Zn3phase and HA are identified in the experimental composite. The Mg(OH)2and Hydroxyapatite were found on the corrosion products in the simulated body fluid.

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