Ti–51at%Ni shape memory alloys(SMAs) were successfully produced via a powder metallurgy and microwave sintering technique.The influence of sintering parameters on porosity reduction,microstructure,phase transformatio...Ti–51at%Ni shape memory alloys(SMAs) were successfully produced via a powder metallurgy and microwave sintering technique.The influence of sintering parameters on porosity reduction,microstructure,phase transformation temperatures,and mechanical properties were investigated by optical microscopy,field-emission scanning electron microscopy(FE-SEM),X-ray diffraction(XRD),differential scanning calorimetry(DSC),compression tests,and microhardness tests.Varying the microwave temperature and holding time was found to strongly affect the density of porosity,presence of precipitates,transformation temperatures,and mechanical properties.The lowest density and smallest pore size were observed in the Ti–51at%Ni samples sintered at 900°C for 5 min or at 900°C for 30 min.The predominant martensite phases of β2 and β19′ were observed in the microstructure of Ti–51at%Ni,and their existence varied in accordance with the sintering temperature and the holding time.In the DSC thermograms,multi-transformation peaks were observed during heating,whereas a single peak was observed during cooling;these peaks correspond to the presence of the β2,R,and β19′ phases.The maximum strength and strain among the Ti–51at%Ni SMAs were 1376 MPa and 29%,respectively,for the sample sintered at 900°C for 30 min because of this sample's minimal porosity.展开更多
A NiTi shape memory alloy （SMA） modified by Ta ion implantation was subjected to oxidation treatment in air at 723 and 873 K. Atomic force microscopy （AFM）, Auger electron spectroscopy （AES）, and grazing inciden...A NiTi shape memory alloy （SMA） modified by Ta ion implantation was subjected to oxidation treatment in air at 723 and 873 K. Atomic force microscopy （AFM）, Auger electron spectroscopy （AES）, and grazing incidence X-ray diffraction （GIXRD） measurements were conducted to investigate the surface characteristics, including surface topography, elemental depth profiles, and surface phase structures. The surface roughness of the Ta-implanted NiTi increases after oxidation, and the higher the oxidation temperature is, the larger the value is. The surface of the Ta-implanted NiTi oxidized at 723 K is a nanolayer mainly composed of TiO2/Ta2O5 and TiO with depressed Ni content. The Ta-implanted NiTi oxidized at 873 K is mainly covered by rutile TiO2 in several micrometers of thickness. Potentiodynamic polarization tests indicated that the corrosion resistance of the Ta-implanted NiTi was improved after thermal oxidation at 723 K, but a negative impact was found for the Ta-implanted NiTi oxidized at 873 K.展开更多
The effect of aluminium content and solution heat treatment in α+β phase region on the shape memory characteristics and mechanical properties of cold wrought Cu-Al-Ni-Mn-Ti alloy are studied in this paper. Results i...The effect of aluminium content and solution heat treatment in α+β phase region on the shape memory characteristics and mechanical properties of cold wrought Cu-Al-Ni-Mn-Ti alloy are studied in this paper. Results indicate that the transformation temperature (Tt) of Cu-Al-Ni-Mn-Ti alloy reduces obviously with the increase of the amount of α-phase. During aging at 623 K, Tt increases at first up to a peak value, then decreases with prolongation of aging time. Life time of heat resistance of the alloy at high temperatures is improved with increase of the amount of α-phase, this life time becomes poor with Bainite precipitation. When the amount of α-phase is less than 5%, the ratio of shape recovery brought about by the solution heat treatment in α+β phase region is almost not effected. However, plasticity of the alloy increases obviously as aluminium content decreases. We believe that improving cold workability of Cu-Al-Ni-Mn-Ti alloy and keeping good heat resistant property and shape memory effects are possible by means of reducing the content of aluminium and solulion heat treatment in α+β phase region.展开更多
Shape memory alloys (SMA) have been applied to a wide variety of applications in a number of different fields such as aeronautical applications, sensors/actuators, medical sciences as well as orthodontics. It is a hot...Shape memory alloys (SMA) have been applied to a wide variety of applications in a number of different fields such as aeronautical applications, sensors/actuators, medical sciences as well as orthodontics. It is a hot topic to enhance the anti-corrosion ability of orthodontic wires for clinical applications. In this letter, a very nice fractal structure, micro-domains with identical nanometer sized grooves, was ob- tained on the surfaces of the orthodontic wires with an oxygen plasma and acid corrosion. The concave parts of the grooves were dominated by titanium and convex parts were the same as the bulk wires. The micro-nano fractal structure generated a hydrophobic surface with the largest contact angle to water being about 157°. The titanium dominated nanolayer and the hydrophobicity of the surface resulted in jointly the great improvement of the anti-corrosion ability of the orthodontic wires. Because the fractal structures of the wires were formed automatically when they immersed in acidic environment, hence, the self-protection of the oxygen plasma-treated orthodontic wires in acidic environment indicates their potential applications in orthodontics, and should be also inspirable for other applications of SMA materials.展开更多
目的:探讨胸腔镜镍钛记忆合金环抱器内固定对多发性肋骨骨折患者的影响。方法:选取2021年5月—2022年8月蚌埠医学院第二附属医院收治的84例多发性肋骨骨折患者。根据随机数表法将其分为对照组和观察组,各42例。对照组采取保守治疗,观察...目的:探讨胸腔镜镍钛记忆合金环抱器内固定对多发性肋骨骨折患者的影响。方法:选取2021年5月—2022年8月蚌埠医学院第二附属医院收治的84例多发性肋骨骨折患者。根据随机数表法将其分为对照组和观察组,各42例。对照组采取保守治疗,观察组在对照组基础上给予胸腔镜镍钛记忆合金环抱器内固定治疗。比较两组临床疗效,康复情况,术前、术后12 h、7 d的疼痛程度,术前与术后7 d肺功能及并发症。结果:观察组总有效率高于对照组,差异有统计学意义(P<0.05)。观察组术后下床时间、呼吸机使用时间、骨折愈合时间、住院时间均短于对照组,差异有统计学意义(P<0.05)。术后12 h、7 d,两组视觉模拟评分法(visual analogue scale,VAS)评分较术前降低,且观察组VAS评分低于对照组,差异有统计学意义(P<0.05)。术后7 d,两组最大自主通气量(maximal voluntary ventilation,MVV)占预计值的百分比(the value of the estimated percentage of the maximal voluntary ventilation,MVV%pred)均升高,观察组高于对照组,差异有统计学意义(P<0.05),两组术后7 d第1秒用力呼气容积(forced expiratory volume in one second,FEV_(1))占预计值的百分比(the value of the estimated percentage of the forced expiratory volume in one second,FEV_(1)%pred)比较,差异无统计学意义(P>0.05)。观察组并发症发生率低于对照组,差异有统计学意义(P<0.05)。结论:胸腔镜镍钛记忆合金环抱器内固定应用于多发性肋骨骨折患者,可提高患者疗效,促进患者术后康复,减轻患者疼痛,降低并发症发生率。展开更多
基金financial support under the University Research Grant No.Q.J130000.3024.00M57
文摘Ti–51at%Ni shape memory alloys(SMAs) were successfully produced via a powder metallurgy and microwave sintering technique.The influence of sintering parameters on porosity reduction,microstructure,phase transformation temperatures,and mechanical properties were investigated by optical microscopy,field-emission scanning electron microscopy(FE-SEM),X-ray diffraction(XRD),differential scanning calorimetry(DSC),compression tests,and microhardness tests.Varying the microwave temperature and holding time was found to strongly affect the density of porosity,presence of precipitates,transformation temperatures,and mechanical properties.The lowest density and smallest pore size were observed in the Ti–51at%Ni samples sintered at 900°C for 5 min or at 900°C for 30 min.The predominant martensite phases of β2 and β19′ were observed in the microstructure of Ti–51at%Ni,and their existence varied in accordance with the sintering temperature and the holding time.In the DSC thermograms,multi-transformation peaks were observed during heating,whereas a single peak was observed during cooling;these peaks correspond to the presence of the β2,R,and β19′ phases.The maximum strength and strain among the Ti–51at%Ni SMAs were 1376 MPa and 29%,respectively,for the sample sintered at 900°C for 30 min because of this sample's minimal porosity.
基金supported by the National Natural Science Foundation of China (No.50971007)the Program for New Century Excellent Talents in Universities from the Ministry of Education of China (No.NCET-09-0024)
文摘A NiTi shape memory alloy （SMA） modified by Ta ion implantation was subjected to oxidation treatment in air at 723 and 873 K. Atomic force microscopy （AFM）, Auger electron spectroscopy （AES）, and grazing incidence X-ray diffraction （GIXRD） measurements were conducted to investigate the surface characteristics, including surface topography, elemental depth profiles, and surface phase structures. The surface roughness of the Ta-implanted NiTi increases after oxidation, and the higher the oxidation temperature is, the larger the value is. The surface of the Ta-implanted NiTi oxidized at 723 K is a nanolayer mainly composed of TiO2/Ta2O5 and TiO with depressed Ni content. The Ta-implanted NiTi oxidized at 873 K is mainly covered by rutile TiO2 in several micrometers of thickness. Potentiodynamic polarization tests indicated that the corrosion resistance of the Ta-implanted NiTi was improved after thermal oxidation at 723 K, but a negative impact was found for the Ta-implanted NiTi oxidized at 873 K.
文摘The effect of aluminium content and solution heat treatment in α+β phase region on the shape memory characteristics and mechanical properties of cold wrought Cu-Al-Ni-Mn-Ti alloy are studied in this paper. Results indicate that the transformation temperature (Tt) of Cu-Al-Ni-Mn-Ti alloy reduces obviously with the increase of the amount of α-phase. During aging at 623 K, Tt increases at first up to a peak value, then decreases with prolongation of aging time. Life time of heat resistance of the alloy at high temperatures is improved with increase of the amount of α-phase, this life time becomes poor with Bainite precipitation. When the amount of α-phase is less than 5%, the ratio of shape recovery brought about by the solution heat treatment in α+β phase region is almost not effected. However, plasticity of the alloy increases obviously as aluminium content decreases. We believe that improving cold workability of Cu-Al-Ni-Mn-Ti alloy and keeping good heat resistant property and shape memory effects are possible by means of reducing the content of aluminium and solulion heat treatment in α+β phase region.
基金Supported by the National Natural Science Foundation of China (Grant No. 30572067)Ministry of Science and Technology of China
文摘Shape memory alloys (SMA) have been applied to a wide variety of applications in a number of different fields such as aeronautical applications, sensors/actuators, medical sciences as well as orthodontics. It is a hot topic to enhance the anti-corrosion ability of orthodontic wires for clinical applications. In this letter, a very nice fractal structure, micro-domains with identical nanometer sized grooves, was ob- tained on the surfaces of the orthodontic wires with an oxygen plasma and acid corrosion. The concave parts of the grooves were dominated by titanium and convex parts were the same as the bulk wires. The micro-nano fractal structure generated a hydrophobic surface with the largest contact angle to water being about 157°. The titanium dominated nanolayer and the hydrophobicity of the surface resulted in jointly the great improvement of the anti-corrosion ability of the orthodontic wires. Because the fractal structures of the wires were formed automatically when they immersed in acidic environment, hence, the self-protection of the oxygen plasma-treated orthodontic wires in acidic environment indicates their potential applications in orthodontics, and should be also inspirable for other applications of SMA materials.
文摘目的:探讨胸腔镜镍钛记忆合金环抱器内固定对多发性肋骨骨折患者的影响。方法:选取2021年5月—2022年8月蚌埠医学院第二附属医院收治的84例多发性肋骨骨折患者。根据随机数表法将其分为对照组和观察组,各42例。对照组采取保守治疗,观察组在对照组基础上给予胸腔镜镍钛记忆合金环抱器内固定治疗。比较两组临床疗效,康复情况,术前、术后12 h、7 d的疼痛程度,术前与术后7 d肺功能及并发症。结果:观察组总有效率高于对照组,差异有统计学意义(P<0.05)。观察组术后下床时间、呼吸机使用时间、骨折愈合时间、住院时间均短于对照组,差异有统计学意义(P<0.05)。术后12 h、7 d,两组视觉模拟评分法(visual analogue scale,VAS)评分较术前降低,且观察组VAS评分低于对照组,差异有统计学意义(P<0.05)。术后7 d,两组最大自主通气量(maximal voluntary ventilation,MVV)占预计值的百分比(the value of the estimated percentage of the maximal voluntary ventilation,MVV%pred)均升高,观察组高于对照组,差异有统计学意义(P<0.05),两组术后7 d第1秒用力呼气容积(forced expiratory volume in one second,FEV_(1))占预计值的百分比(the value of the estimated percentage of the forced expiratory volume in one second,FEV_(1)%pred)比较,差异无统计学意义(P>0.05)。观察组并发症发生率低于对照组,差异有统计学意义(P<0.05)。结论:胸腔镜镍钛记忆合金环抱器内固定应用于多发性肋骨骨折患者,可提高患者疗效,促进患者术后康复,减轻患者疼痛,降低并发症发生率。
基金National Natural Science Foundation of China under grant(50671037)the SRGgrant fromthe Research Committee of the CityUof HK(Project#:7001999)the Central Allocation Grant Scheme of the research Grants Council of the Hong Kong Special Administrative Region,China(CityU1/04C)
