Papers by Author: Xing Jun Liu

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Authors: Yun Qing Ma, Shui Yuan Yang, San Li Lai, Shi Wen Tian, Cui Ping Wang, Xing Jun Liu
Abstract: The rare earth element Gd is added to Ni53Mn22Co6Ga19 high-temperature shape memory alloy to refine the grain size and adjust the distribution of γ phase, and their microstructure, martensitic transformation behaviors, mechanical and shape memory properties were investigated. The results show that the grain size is obviously decreased and the γ phase tends to segregate at grain boundaries with increasing Gd content. Small amounts of Gd-rich phase were formed with 0.1 at.% Gd addition. The martensitic transformation temperature abruptly increases with 0.1 at.% Gd addition, then almost keeps constant with further increasing Gd content. The addition of 0.1 at.% Gd is proved to be beneficial to both tensile stress and strain before fracture, but negative to the shape-memory effect.
Authors: Xu Liang Liu, Yun Qing Ma, Shui Yuan Yang, Yun Neng Wang, Cui Ping Wang, Xing Jun Liu
Abstract: The effects of trace boron on microstructure and mechanical properties of β type Ti-9V-3Al-3Cr-3Zr-3.5Mo (wt. %) alloy have been investigated in this study. Upon the addition of 0.02 wt. % boron, the grain size of the B-modified alloy was almost four times smaller than that of the B-free alloy. Accordingly, the tensile strength and elongation of B-modified alloy increased from 712 MPa and 14.6 % to 813 MPa and 17.9 %, respectively, mainly due to the effect of grain refinement.
Authors: Yun Neng Wang, Yun Qing Ma, Shui Yuan Yang, Xu Liang Liu, Cui Ping Wang, Xing Jun Liu
Abstract: The effects of Nb addition on microstructures, Young’s moduli, tensile properties of Ti-30Ta-xNb (x = 21, 24, 27, 30, wt. %) alloys were investigated in this study. The results show that dual phases containing β phase and a little α" martensite were observed when x = 21 and 24, whereas single β phase is present when x = 27 and 30. A minimum Young’s modulus of 52.13 GPa was obtained in Ti-30Ta-21Nb alloy. Ti-30Ta-xNb alloys exhibit high strength-to-modulus ratios, showing their great potentials to develop as new candidates for biomedical applications.
Authors: Shui Yuan Yang, Cui Ping Wang, Yu Su, Xing Jun Liu
Abstract: The evolutions of microstructure and phase transformation behavior of Cu-Al-Fe-Nb/Ta high-temperature shape memory alloys under the quenched and aged states were investigated in this study, including Cu-10wt.% Al-6wt.% Fe, Cu-10wt.% Al-4wt.% Fe-2wt.% Nb and Cu-10wt.% Al-4wt.% Fe-2wt.% Ta three types alloys. The obtained results show that after quenching, Cu-10wt.% Al-6wt.% Fe alloy exhibits two-phase microstructure of β′1 martensite + Fe (Al,Cu) phase; Cu-10wt.% Al-4wt.% Fe-2wt.% Nb alloy also has two-phase microstructure of (β′1 + γ1 martensites) + Nb (Fe,Al,Cu)2 phase; Cu-10wt.% Al-4wt.% Fe-2wt.% Ta alloy is consisted of three-phase of (β′1 + γ1 martensites) + Fe (Al,Cu,Ta) + Ta2(Al,Cu,Fe)3 phases. However, α (Cu) phase precipitates after aging for three alloys; and Fe (Al,Cu,Nb) phase is also present in Cu-10wt.% Al-4wt.% Fe-2wt.% Nb alloy. All the studied alloys exhibit complicated martensitic transformation behaviors resulted from the existence of two types martensites (β′1 and γ1).
Authors: Yun Qing Ma, Shui Yuan Yang, Ryosuke Kainuma, Kiyohito Ishida, Cui Ping Wang, Xing Jun Liu
Abstract: The phase equilibria at 900 °C and B2/L21 order-disorder transition in the Ni-Mn-Ga ternary system were investigated by analyzing the equilibrated alloys and diffusion couples using a combination of techniques. It was confirmed that a bcc single phase region exists in a wide composition range at 900 °C, and the critical temperatures of B2/L21 order-disorder transition were determined in Ni-50 at.% section, which exhibits a maximal ordering transition temperature of 796 at Mn content of 25 at.%. The obtained results will be helpful for the preparation and annealing of Ni-Mn-Ga alloys in the specific temperature.
Authors: Zhan Shi, Xiao Fei Li, Tian Hui Chi, Cui Ping Wang, Xing Jun Liu, Shui Yuan Yang, Yong Lu, Jia Jia Han, W. B. Liu
Abstract: Equivalent magnetic circuit method is a rapid calculation method used in magnetic circuit simulation. But for a long time this method can’t be used widely because the algorithm is not general and there is no commercial software developed for this method. In this paper, general software for magnetic circuit calculation was developed using LabVIEW language. Quasi-Newton algorithm was used in solving nonlinear Kirchhoff equation of magnetic circuit in this software. The project file in this software can be shared freely in different calculations. This software is expected to save the time-cost in the design of new product.
Authors: Yun Qing Ma, Cheng Bao Jiang, Yan Li, Cui Ping Wang, Xing Jun Liu
Abstract: A strong need exists to develop new kinds of high-temperature shape-memory alloys. In this study, two series of CoNiGa alloys with different compositions have been studied to investigate their potentials as high-temperature shape-memory alloys, with regard to their microstructure, crystal structure, and martensitic transformation behavior. Optical observations and X-ray diffractions confirmed that single martensite phase was present for low cobalt samples, and dual phases containing martensite and γ phase were present for high cobalt samples. It was also found that CoNiGa alloys in this study exhibit austenitic transformation temperatures higher than 340°C, showing their great potentials for developing as high-temperature shape-memory alloys.
Authors: Cui Ping Wang, Yu Ding Liu, Shui Yuan Yang, Xing Jun Liu
Abstract: The microstructure and phase transformation behavior of Ni-Mn-Fe high-temperature shape memory alloys including Ni40+xFe10Mn50-x (x = 0, 10) were investigated. The results show that both two alloys exhibit single fcc γ phase annealed at 900°C for 1 day. When these quenched alloys are again annealed at 500°C for 20 days, they almost exhibit main tetragonal θ martensite. The microstructural evolutions are consistent with the results of phase transformation measurements. It is clearly found that there is an irreversible phase transformation around 480°C ~ 570°C, which is associated with the formation of tetragonal θ martensite from γ phase. Afterwards, the reversible martensitic transformation occurs during heating and cooling with very high transformation temperature.
Authors: Yun Qing Ma, Wan Jun Jin, Shui Yuan Yang, Jin Bin Zhang, Yi Xiong Huang, Xing Jun Liu
Abstract: Recently Ni-free Ti-based shape memory alloys have been actively studied for biomedical applications in order to replace Ti-Ni alloys which bear the possibility of Ni-hypersensitivity. In this paper, The Ti-(40-65) Ta (wt. %) alloys have been studied with regard to their microstructure, mechanical and shape memory properties, as well as the effect of heat treatment on their shape memory behaviors. The results show that Ti-40wt. %Ta exhibits single orthorhombic structure (''), Ti-55wt. %Ta mainly '' and a little BCC structure (β), and Ti-65wt. % Ta mainly β and a little '' at room temperature. The tensile strengths of Ti-Ta alloys are all over 550 MPa, and the elongations over 17%. The Young’s modulus of Ti-Ta alloys ranges from 66 to 75 GPa, which are closer to the modulus of human bone as compared with that of Ti-6Al-4V alloy. The maximal shape memory strain of 3.32% was obtained in Ti-55wt. %Ta alloy quenched at 1273 K followed by aging at 723 K for 10min. The obtained results will be beneficial for developing Ti-Ta alloys for biomedical applications.
Authors: Yong Lu, Zhen Huai, Shuang Yang, Xing Jun Liu, Cui Ping Wang
Abstract: New Cu–Fe-based ternary systems have been developed to fabricate monolithic porous materials through electrochemical dealloying process in a 1.84 mol/L H2SO4 solution. The microstructures of the porous materials were characterized using X-ray diffraction, scanning electron microscopy and energy dispersive X-ray analysis. The results show that the compositions of the as-melt Cu-Fe-Co and Cu-Fe-Ni alloys have an important effect on the electrochemical dealloying process and microstructures of the monolithic porous materials.
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