Xianglong MENG
,
Wei CAI
,
K.T.Lau
,
L.M.Zhou
,
Liancheng ZHAO
,
null
,
null
材料科学技术（英）
The use of Ni-rich TiNiHf alloys as high temperature shape memory alloys (SMAs) through aging has been presented. For Ni-rich Ti80-xNixHf20 alloys, their phase transformation temperatures are averagely increased more than 100 K by aging at 823 K for 2 h. Especially for the alloys with Ni-content of 50.4 at. pct and 50.6 at. pct, their martensitic transformation start temperatures (Ms) are more than 473 K after aging. TEM observation confirmed that some fine particles precipitate from the matrix during aging. The aged Ni-rich TiNiHf SMAs show the better thermal stability of phase transformation temperatures than the solutiontreated TiNiHf alloys. The fine particles precipitated during aging should be responsible for the increase of phase transformation temperatures and its high stability.
关键词:
TiNiHf alloy
,
null
,
null
,
null
Xin GAO
,
Yufeng ZHENG
,
Wei CAI
,
Su ZHANG
,
Liancheng ZHAO
材料科学技术（英）
The microstructure, phase transformation, compression property and strain recovery characteristics of equiatomic TaRu super high temperature shape memory alloy have been studied by optical microscope, XRD, DTA, compression tests and TEM observations. When cooling the alloy specimen from high temperature to the room temperature, (parent phase)→ (interphase)→ (martensite) two-step phase transformations occur. The microstructure at room temperature show regularly arranged band morphology, with the monoclinic crystal structure. The twinning relationship between the martensite bands is determined to be (101) of Type I. Reorientation and coalescence of the martensite bands inside the variant happened during compression at room temperature. The → reversible transformation contributes mainly the shape memory effect, with the maximum completely recovery strain of 2%.
关键词:
TaRu alloy
,
null
,
null
,
null
Qingfu CHEN
,
Liancheng ZHAO
,
R.Stalmans
,
J. Van Humbeeck
材料科学技术（英）
The superelastic behaviors of different isothermal treated Cu-13.SAl-4.ONi (mass fraction) single crystals were studied by applying tensile stress along <001> of the β phase. The different isothermal specimens have different superelastic behavior due to the change of the ratio of stress-induced γ1’and β’. The superelasticity ofγ1 phase tends to that of g, phase with cycling. Typical stabilization of stress-induced martensite above Ap results in residual deformation. Due to the reverse transformation of γ1’, there is a deviation of pseudo-yield stress form linear relation with temperature at relatively low stress.
关键词:
Dongyan TANG
,
Liangsheng QIANG
,
Zheng JIN
,
Liancheng ZHAO
材料科学技术（英）
Interpenetrating polymer networks (IPNs) composed of acrylate-modified polyurethane (PU)/unsaturated polyester (UP) resin $via$ simultaneous polymerization with various component ratios of PU/UP were prepared. The polymerization processes of IPNs were traced through infrared spectrum (IR) techniques, by which the phase separation in systems could be controlled effectively. Results for the morphology and miscibility among multiple phases of IPNs, obtained by transmission electron microscope (TEM) indicated that the domains between two phases were constricted in nanometer scales. The dynamic mechanical thermal analyzer (DMTA) detection results revealed that the loss factor (tanδ) and loss modulus (E'') increased with the polyurethane amounts in system, and the peak value in curves of tanδ and E'' appeared toward low temperature ranges. Maximum tanδ values of all samples were above 0.3 in the nearly 50℃ ranges. Also, the mechanical properties of PU/UP IPNs were studied in detail.
关键词:
Interpenetrating polymer networks (IPNs)
,
null
,
null
,
null
Fu LIU
,
Fuping WANG
,
Tadao Shimizu
,
Kaoru Igarashi
,
Liancheng ZHAO
材料科学技术（英）
The ceramic coating was formed by using microarc oxidation (MAO) in the electrolytic solution of β-Glycerophosphate sodium salt pentahydrate (β-GP) and calcium acetate (CA). The microstructure, phase structure and phase composition were investigated with scanning electron microscopy (SEM), atomic force microscope (AFM), energy dispersive X-ray microanalyser (EDX), X-ray photoelectron spectroscopy (XPS), electron probe micro analyzer (EPMA) and X-ray diffraction (XRD). Investigation of the chemical composition of the coating with EDX revealed that Ca and P of high concentration existed in oxide films. XRD patterns indicated that the oxide film was composed of only anatase at low voltage discharge, and that rutile peaks appear in addition to anatase peak with increasing MAO voltage. Despite the existence of Ca and P, compounds concerning Ca and P were not detected in the oxide film.
关键词:
Microarc oxidation
,
null
,
null
Liming WANG
,
Yufeng ZHENG
,
Wei CAI
,
Xianglong MENG
,
Liancheng ZHAO
材料科学技术（英）
The effect of thermal cycling under loading on martensitic transformation and two-way shape memory effect was investigated for Ti-49.8 at, pet Ni alloy. It is shown that M-s, and M-f temperature increase with increasing the number of cycles, while A(s) and A(f) temperature decrease during thermal cycling. The total strain at and permanent strain epsilon (p) increase with increasing applied stress and number of cycles. The two-way shape memory effect can be improved by proper thermal cycling training under loading, while excessively high applied stress results in the deterioration of TWSME. The reason for the changes in martensitic transformation characteristics and two-way shape memory effect during thermal cycling under loading is discussed based on the analysis of microstructure by TEM observations.
关键词:
Shigang XIN
,
Zhaohua JIANC
,
Fuping WANG
,
Xiaohong WU
,
Liancheng ZHAO
,
Tadao SHIMIZU
材料科学技术（英）
The microplasma oxidation process of LY 12 Al alloy in Na2SiO3-KOH-NaAlO2 system has been studied. The voltage-time curve of oxidation process is changed with the variation of current densities. The voltage breakdown and hardness of coating increase with increasing current density. The phase composition, morphologies, element and the distribution of ceramic coating are investigated by XRD, EPMA.
关键词:
Xianglong MENG
,
Wei CAI
,
K.T.LAU
,
L.M.ZHOU
,
Liancheng ZHAO
材料科学技术（英）
The Effect of the thermal cycling training under constant strain on the two-way shape memory effect (TWSME) in a Ti36Ni49Hf15 high temperature shape memory alloy (SMA) has been investigated by bending tests. The results indicated that the training procedure is beneficial to get the better TWSME. The two-way shape memory strain increases with increasing the training strain. And it decreases with increasing the training temperature. The TWSME obtained in the present alloy shows poorer stability compared with that obtained in the TiNi alloys.
关键词:
TiNiHf alloy
,
null
,
null
,
null
Liming WANG
,
Xianglong MENG
,
Wei CAI
,
Liancheng ZHAO
材料科学技术（英）
A two-way shape memory effect (TWSM E) in the Ti46.3Ni44.7Nb9 alloy has been systematically investigated by means of bending test and transmission electron microscopy (TEM) observations. Based on the analysis of the microstructure after training, the mechanism of TWSME in the Ti46.3 Ni44.7Nb9 alloy has been discussed.
关键词:
Qingfu CHEN
,
Wei CAI
,
Liancheng ZHAO
材料科学技术（英）
The paper studied the relationship between microstructure and shape recovery characteristics by using colored microstructure analysis under polarized light on the thermomechanical cycled CuAINi single crystals. The two-way shape memory effect in quenched thin bar resulted from the preferential formation/extinction of martensite variant due to the internal quench stress, and the variant was formed at an angle of about 45 deg. with the tension direction ([001] of the beta phase). Initial thermomechanical cycling under relatively low stress single variant stress-induced martensite was formed at an angle of 45 deg. with the tension and its morphology was a lath of parallel twins. More than one group of variants were formed after several training cycles and such variants also caused tilting of some thermally formed accommodated martensite. By overheating the trained sample containing stabilized multi-variants of stress-induced martensite, very coarse martensite structure with a strong asymmetry was produced, which caused the reverse two-way shape memory effect.
关键词:
