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Zhenjiang, China

Si N.,Jiangsu University | Zhai Y.,Jiangsu University | Si S.,Zhenjiang Innov Alloy Co. | Zhao P.,Jiangsu University | Zheng L.,Jiangsu University
Xiyou Jinshu Cailiao Yu Gongcheng/Rare Metal Materials and Engineering | Year: 2011

Transformation behavior of TiNiCr shape memory alloys with different aging treatment was investigated by DSC, scanning electron microscopy (SEM) and the D/max2500PC automatic X-ray diffraction equipment (XRD). The results indicate that with increasing of the aging temperature, the transformation temperature A s and A f increase but they decrease after 700°C and TiNiCr alloy exhibits B2→R→B19' two-stage martensitic transformation during cooling. Lots of Ti 3Ni 4 precipitants from aging treatment induce R phase transformation. Copyright © 2011, Northwest Institute for Nonferrous Metal Research. Published by Elsevier BV. All rights reserved.

Xu F.,Jiangsu University | Si N.-C.,Jiangsu University | Si S.-H.,Zhenjiang Innov Alloy Co. | Wang H.-Q.,Jiangsu University
Zhuzao/Foundry | Year: 2012

The Cu-12Al-2.5Mn shape memory alloy was produced by powder metallurgy technology at different sintering temperature. Consequently, the properties and microstructure of the alloy that sintered at different temperature were compared by SEM, metallographic observation, EDS, hardness test and shape memory effect test. Then the optimum sintering temperature was obtained. The results show that the bonding way between elements is metallurgical bonding and the alloying rate rises with the increase of sintering temperature, the optimum sintering temperature ranges from 850°C to 900°C. The edge of the sample has higher hardness, and the alloy sintered at 850°C and 900°C has uniform and high hardness value after quenched, the hardness of the alloy sintered at 850°C is HRB 42.5, while the hardness of the alloy sintered at 900°C is HRB 52. The shape memory effect of the alloy sintered at 850°C is better than that sintered at 900°C.

Si N.-C.,Jiangsu University | Hu Y.,Jiangsu University | Liu G.-L.,Jiangsu University | Si S.-H.,Zhenjiang Innov Alloy Co. | And 2 more authors.
Zhuzao/Foundry | Year: 2014

The influence of Ni-45Ti alloys and mechanical vibration on microstructure and mechanical properties of ZA27 alloys and thermal fatigue properties has been researched in this article. The microstrucrure and thermal fatigue cracking have been observed by light microscopy. The results show that: the appropriate amount of Ni-45Ti alloys were added and mechanical vibration alloy, the organization has been significantly refined, mechanical properties and thermal fatigue performance is improved significantly. With the increase of Ni-45Ti content, tensile strength and elongation first increase and then decrease. When the Ni-45Ti content was 0.6%, optimal mechanical properties of alloys were obtained. The crack length is the shortest and ZA27 alloy has the best thermal fatigue with 0.6%Ni-45Ti alloys and mechanical vibration alloy.

Wu Y.-Y.,Jiangsu University | Si N.-C.,Jiangsu University | Liu G.-L.,Jiangsu University | Si S.-H.,Zhenjiang Innov Alloy Co. | Zhao B.,Jiangsu University
Zhuzao/Foundry | Year: 2014

The effect of Mn addition on microstructures, mechanical properties and friction wear under oil lubrication of ZA43 alloy was investigated. The results show that the microstructure of ZA43 alloys were significantly refined with adding proper amount of Mn. ZA43 alloy has better comprehensive mechanical properties when the addition of Mn is 0.55%. With the increase of Mn additive content, the wear mechanism changes from mixed form of adhesive wear and abrasive wear to only form of abrasive wear under 800 N. The rich Mn phase is main form in ZA43 alloy, and was distributed at the grain boundary, not only improved the elevated temperature strength of alloys, but also dispersed the shear stress and hindered the expansion of microcracks as hard spots. As a result, the wear resistances of the ZA43 alloys were improved.

Si N.-C.,Jiangsu University | Xu N.-J.,Jiangsu University | Si S.-H.,Zhenjiang Innov Alloy Co. | Li Y.-D.,Jiangsu University | Shi J.,Jiangsu University
Cailiao Gongcheng/Journal of Materials Engineering | Year: 2011

The drop-down 5 kg crucible directional solidification equipment was used and the directional solidification experiment of Al-4.5%Cu alloy was carried out. The primary dendrite spacing of Al-4.5%Cu alloy under the conditions of different temperature gradient was studied. The results show that with the increasing of the temperature gradient, the primary dendrite spacing becomes smaller, meticulous and upright in other solidification parameters remaining unchanged. The basic shape is parallel to the distribution, meanwhile, the computed value of the primary dendrite arm spacing is closed to value with the Hunt calculated. The test measures the value of primary dendrite arm spacing in a regressive curve: y=2843478.3x2-70217.4x+543.8. With a higher temperature gradient to simulate the experimental values, the availability of λ1=26.7G-0.5-135.9 is got. The primary dendrite arm spacing λ1 almost is linear with G-0.5. This is consistent with Hunt analyzed result.

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