Zhenyu YUAN
材料科学技术（英文）
The superelastic properties of NiTi thin films prepared with sputtering were studied. To characterize their superelasticity, tensile and bulging and indentation tests were performed. The measured mechanisms using these three methods were compared, and the factors that influence superelasticity were described.
关键词:
Shape memory alloy
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memory
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alloy
,
NiTi
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thin
,
film
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Super
Yanjun ZHENG
,
Lishan CU
,
IYan LI
,
Dazhi YANG
材料科学技术（英文）
The reverse martensitic transformation of TiNi shape memory alloy fibers embedded in a pure aluminum matrix was studied in this paper. Results showed that the phase composition of the TiNi alloy fibers prior to prestraining at the room temperature had a significant influence on the differential scanning calorimetry (DSC) results of the composites. By a comparison to the high temperature X-ray diffraction (XRD) results, it was confirmed that the martensite was divided into two groups: the self-accommodating martensite (SAM) and the preferentially oriented martensite (POM). The evolving process of the separation of martensite was discussed.
关键词:
Shape memory alloy
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null
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null
,
null
Shihai GUO
,
Yanghuan ZHANG
,
Jianliang LI
,
Baiyun QUAN
,
Yan QI
,
Xinlin WANG
材料科学技术（英文）
A magnetic shape memory alloy with nonstoichiometric Ni50Mn27Ga23 was prepared by using melt-spinning technology. The martensitic transformation and the magnetic-field-induced strain (MFIS) of the polycrystalline melt-spun ribbon were investigated. The experimental results showed that the melt-spun ribbons underwent thermal-elastic martensitic transformation and reverse transformation in cooling and heating process and exhibited typical thermo-elastic shape memory effect. However the start temperature for martensitic transformation decreased from 286 K for as-cast alloy to 254 K for as-quenched ribbon and Curie temperature remains approximately constant. A particular internal stress induced by melt-spinning resulted in the formation of a texture structure in the ribbons, which made the ribbons obtain larger martensitic transformation strain and MFIS. The internal stress was released substantially after annealing, which resulted in a decrease of MFIS of the ribbons.
关键词:
Shape memory alloy
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null
,
null
,
null
Zhirong HE
,
Fang WANG
,
Jing'en ZHOU
材料科学技术（英文）
The basic martensitic transformation (MT) properties of Ru50Ta50 alloy, i.e. MT temperature (MTT), temperature hysteresis (ΔT), and MT heat (ΔH) were investigated in this paper. The effects of heat treatment and thermal cycling on MT behavior of Ru50Ta50 alloy, the deformation and microstructure characteristics of Ru50Ta50 alloy were also studied for its engineering application as high temperature actuator/sensor materials by means of differential scanning calorimetry, X-ray diffraction, transmission electron microscope, optical microscope, and hardness test. The results showed that a two-stage reversible MT takes place in Ru50Ta50 alloy. The two-stage MT starting temperatures (MS1 , MS2 ) and the temperature hysteresis (ΔT1, ΔT2) are 1047, 784 and 11, 14℃, respectively. No significant effect of aging treatment and thermal cycling on MTT and ΔT of Ru50Ta50 alloy were observed, but ΔH decreases slowly with increasing thermal cycles. The hardness and brittleness of Ru50Ta50 alloy are high. The deformation mode of RuTa alloys is twinning.
关键词:
RuTa alloy
,
热处理
,
热循环
,
形状记忆合金
,
Ru
Wei JIN
,
Ying YAN
,
Jian WANG
,
Mingzhou CAO
,
Rui YANG
材料科学技术（英文）
The mechanical behavior and the effect of pre-strain on recovery behavior of Ti50Ni47Fe3 (at. pct) alloy were investigated systematically by tensile and recovered tests accompanied by electrical resistance measurement. Ti50Ni47Fe3 alloy has different deformation behaviors at different temperature ranges, the deformation curves in different temperature range can be classified into four kinds. The start temperature of recovery increases with the increase of pre-strain. There exists an optimal deformation condition, at which the specimen exhibits maximum free recovery strain. With increasing pre-strain the recovery stress increases and reaches the maximum at 8% pre-strain. R-phase to parent transition offered about 0.2% recovery strain. With pre-strain increasing the recovery stress increases and reaches to the maximum at 8% pre-strain. The recovery stress is corresponding with the critical stress of stress-induced martensitic transformation.
关键词:
Deformation
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null
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null
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null
,
null
Qingchao TIAN
,
Jiansheng WU
,
Yifeng CHENG
材料科学技术（英文）
Ti50.6Pd30Ni19.4 and Ti51Pd28Ni21(Ce) alloys have been prepared under various temperatures for long time annealing. Differential scanning calorimetery (DSC), X-ray diffraction (XRD) and tensile test were employed to investigate the phase transformation behavior and superelasticity of the alloys. It has been found that the phase transformation temperature of Ti50.6Pd30Ni19.4 is about 40℃ higher than that of Ti51Pd28Ni21(Ce), and do not change much with different annealed temperature. Obvious superelasticity is retained in Ti50.6Pd30Ni19.4 alloy annealed at 400℃ for 18 h, and annealing at higher temperature shows a deterioration of this property. The Ce addition in Ti51Pd28Ni21(Ce) alloy significantly delays recrystallization, increases yied strength and elastic modulus, but the superelasticity is poor.
关键词:
TiNi-Pd
,
null
,
null
