Effect of heat treatment on shape memory properties of ductile CuAlMn alloys

The effect of heat treatment on shape memory properties of the ductile CuAlMn alloys was studied. The results show that the heating temperature for the solution treatment should be around 100 ℃ above the transformation temperature in order to obtain good shape memory properties, heating for 10 min at this temperature doesn’t have much influence on the shape memory properties, faster cooling rate helps to obtain good shape memory properties and the shape recovery rate(SRR) decreases with raising ageing temperatures. For Cu 16Al 10Mn alloy, the heat treatment process to acquire higher recovery rate is heating at 800 ℃ for 15 min, quenching into ice water and ageing below 150 ℃ for 15 min. For Cu 17Al 10Mn alloy, the process is the same except heating at 700 ℃.[

EFFECTS OF HEAT TREATMENT ON TENSILE PROPERTIES AND SHAPE MEMORY EFFECTS OF Ni-Ti-Nb ALLOY

ＥＦＦＥＣＴＳＯＦＨＥＡＴＴＲＥＡＴＭＥＮＴＯＮＴＥＮＳＩＬＥＰＲＯＰＥＲＴＩＥＳＡＮＤＳＨＡＰＥＭＥＭＯＲＹＥＦＦＥＣＴＳＯＦＮｉＴｉＮｂＡＬＬＯＹ①ＺｈｅｎｇＹｕｆｅｎｇ，ＣａｉＷｅｉ，ＬｕｏＹｉｃｈｕｎ，ＺｈａｏＬｉａｎｃｈｅｎｇＳｃｈｏｏ...

Transformation behavior and shape memory effect of Ti_(50-x)Ni_(48)Fe_2Nb_x alloys by aging treatment

The influence of aging treatment on transformation behavior and shape memory of the Ti 50_x Ni_(48) Fe_2 Nb_x(x=0,0.6,0.8,1.0,and 1.2) alloys was investigated using differential scanning calorimeter(DSC),mechanical drawing machine,and microhardness tester in this paper.It is indicated that the aging treatment has a significant effect on the phase transformation temperatures(M_s,M_f,M_p,A_s,A_f,and A_p) and microhardness of the samples.The phase transformation temperatures are found to decrease initially with the increasing aging temperature from 300 to 500 ℃ and increase with further increase of the aging temperature.The aging treatment at intermediate temperature between 400 and 500 ℃ results in an improved shape memory effect.In addition,the highest microhardness value is also obtained.

The Two-step Reverse Martensitic Transformations of TiNi Shape Memory Alloy Based on Solution-treatment and Aging

A TiNi-alloy is solution-treated in a vacuum furnace of 6.7×10^-3 Pa at 1 223 K for 3.6 ks, and then aged at 773 K for 1.8 ks. The differential scanning calorimetry （DSC） measurements show that after the heat-treatment, takes place a two-step reverse Martensitic transformation, from which results the two-stage recovery strain in a prestrained Martensitic TiNi-alloy wire during heating. The Vickers microhardness indentation test in cross-sectional areas of the TiNi-alloy wire indicates the compositional heterogeneity between its surface layers and its inside. The fact that the sizes of the indentation in surface layers smaller than those in the inside bears witness to the existence of slightly harder surface layers. It is believed that these phenomena are related to the compositional fluctuation caused by the evaporation and oxidization of Ti-element during the solution-treatment and heterogeneity formed during the subsequent aging treatment.

Effects of Heat Treatment and Thermal Cycling on Martensitic Transformation Behavior of Ni_(59)Al_(11)Mn_(30) High Temperature Shape Memory Alloy

A reversible martensitic transformation (MT) takes place during cooling and heating in the solution quenched and the solution quenched plus aged Ni59AlHMn30 alloy The MT temperature increases with increasing solution temperature. The excellent MT characteristics can be obtained from a process of lOOCTC solution quenched plus 400 °C aged. Follow this process, the MT start temperature (Ms) and the reverse MT finish temperature (Af) are 469*C and 548"C, respectively. The martensitic stabilization effect in the solution quenched and aged Ni59AlnMn3o alloy is observed as an increase in the Af temperature of the first reverse MT during thermal cycles. This stabilization effect vanishes from the second thermal cycle. Thermal cycling can enhance the stability of the reversible MT. The microstructure of the quenched NisgAlnMnjo alloy consists of martensite (M) and gamma phase. The volume fraction of gamma phase is about 40%. The substructure of M and gamma phase is twins and dislocations, respectively. The hardness of M is higher than that of gamma phase. After aging treatment the basic phases of alloy do not change, but the hardness of the phases increases.

Effects of H_2O_2 pretreatment on surface characteristics and bioactivity of NaOH-treated NiTi shape memory alloy

The effects of H2O2 pretreatment on the surface characteristics and bioactivity of NaOH-treated NiTi shape memory alloy(SMA)were investigated by scanning electron microscopy,X-ray diffraction,X-ray photoelectron spectroscopy,Raman spectra,Fourier transform infrared spectroscopy as well as a simulated body fluid(SBF)soaking test.It is found that the H2O2 pretreatment can lead to the direct creation of more Ti—OH groups and the decrease in the amount of Ni2O3,Na2TiO3 and remnant NiTi phases on the surfaces of bioactive NiTi SMA prepared by NaOH treatment.As a result,the induction period of apatite formation is shortened by dispensing with the slow kinetic formation process of Ti—OH groups via an exchange of Na+ ions from Na2TiO3 phase with H3O+ ions in SBF,which indicates that the bioactivity of NaOH-treated NiTi SMA can be further improved by the H2O2 pretreatment.

Gold热处理镍钛锉在模拟S形根管内的抗疲劳折断性能

目的:比较不同温度下3种新型热处理镍钛锉在模拟S形根管内的抗疲劳折断性能,为临床应用提供依据。方法:选取Gold热处理镍钛锉TruNatomy[25 mm长,26号/0.04锥度(尖段)]与ProTaper Gold[25 mm长,25号/0.08锥度(尖段)]作为实验组,M丝技术镍钛锉ProTaper Next[25 mm长,25号/0.06锥度(尖段)]作为对照组,每种镍钛锉各20支。TruNatomy镍钛锉经过Gold热处理使R相变分离,存在完全的中间R相,使柔软度提高;ProTaper Gold镍钛锉为CM丝镍钛锉,用热处理提高相变温度,常温下以马氏体为主,使柔软度提高,表面经Gold热处理产生中间R相;ProTaper Next镍钛锉则采用M丝技术,M丝常温下以奥氏体为主,经过热机械处理引入硬化马氏体,此类马氏体不参与相变,其弹性模量低于奥氏体,从而使镍钛锉柔软度增高。使用双弯金属模拟根管,分别在室温(24℃)及加热至65℃时检测3种镍钛锉的抗疲劳折断性能,不同温度下的每种镍钛锉各10支(n=10)。对相同温度下不同镍钛锉的疲劳折断圈数(number of cyclic fatigue,NCF)以及折断段长度数据采用单因素方差分析,并进行组间比较,以双侧P<0.05为差异有统计学意义。对相同镍钛锉不同温度下的NCF以及折断段长度数据采用配对样本t检验,并进行两两比较,检验水准均为双侧α=0.05。用扫描电镜进行折断镍钛锉断口分析。结果:3种镍钛锉均为在根尖弯曲处首先发生折断,随后在冠方弯曲处发生折断。室温下,根尖段NCF:Tru-Natomy镍钛锉为344.4±96.6,ProTaper Gold镍钛锉为175.0±56.1,ProTaper Next镍钛锉为133.3±39.7,TruNatomy镍钛锉最高(P<0.05);冠方段NCF:TruNatomy镍钛锉为618.3±75.3,ProTaper Gold镍钛锉为327.5±111.8,ProTaper Next镍钛锉为376.6±67.9,TruNatomy镍钛锉仍为最高(P<0.05)。根尖及冠方折断段长度各组间差异无统计学意义(P>0.05)。加热至65℃,根尖段NCF:TruNatomy镍钛锉为289.6±65.8,ProTaper Gold镍钛锉为187.5±75.4,ProTaper Next镍钛锉为103.0±38.5,TruNatomy镍钛锉最高(P<0.05);冠方段NCF:TruNatomy镍钛锉为454.2±45.4,ProTaper Gold镍钛锉为268.3±31.4,ProTaper Next镍钛锉为283.8±31.7,TruNatomy镍钛锉仍为最高(P<0.05)。与室温相比,TruNatomy镍钛锉冠方段在65℃时的NCF显著下降(P<0.05)。各组镍钛锉断口均符合典型的疲劳折断断口特征。结论:Gold热处理镍钛锉在S形弯曲根管中的抗疲劳折断性能优于M丝镍钛锉。

聚乙二醇/粉煤灰定形相变材料的制备与性能

传统模板法制备介孔硅基材料存在合成工艺复杂、成本高昂的问题。研究以粉煤灰为原料,采用矿相活化和酸刻蚀两步法合成了一种介孔硅基材料,工艺简单且能耗低。以聚乙二醇(PEG)为相变材料,通过真空浸渍法制备了定形复合相变材料。利用扫描电子显微镜(SEM)、傅立叶变换红外光谱(FT-IR)、X射线衍射仪(XRD)、热重(TG)对所制备的材料成分、形貌和热性能等进行了表征。BET测试表明这种介孔硅基材料比表面积可达492 m^(2)/g,孔容为0.42 cm^(3)/g。复合相变材料在105℃下仍然可以保持固体形状,PEG4000的最大质量负载量为61.69%,熔融相变焓为57 J/g。实验表明所制备的定形复合相变材料具有良好的储热性能和热稳定性能,粉煤灰基复合相变材料是一种很有潜力的绿色环保的热能储存材料。

Effect of heat treatment on the transformation behavior and temperature memory effect in TiNiCu wires

The effect of heat treatment on the phase transformation behavior of TiNiCu shape memory alloy wires and the temperature memory effect in this alloy were investigated by the resistance method. These results showed that with increasing annealing temperature and annealing time, the phase transformation temperatures of TiNiCu wires were shifted to higher temperatures in the heating and cooling process. It was also found that incomplete thermal cycles, upon heating the TiNiCu wires, which were arrested at a temperature between the start and finish temperatures of the reverse martensite transformation, could induce a kinetic stop in the next complete thermal cycle. The kinetic stop temperature was closely related to the previous arrested temperature. This phenomenon was defined as the temperature memory effect. The result of this study was consistent with the previous report on the phenomenon obtained using the differential scanning calorimetry method, indicating that temperature memory effect was a common phenomenon in shape memory alloys.

Phase transformation behavior of a TiNiCu shape memory alloy electro-lytically charged with hydrogen

The transformation behavior of a TiNiCu shape memory alloy electrolyticallycharged with hydrogen was investigated by means of different scanning calorimetry (DSC), opticalmicroscope and X-ray diffraction (XRD). The results showed that inter- and inner-granular hydridesformed after charging with hydrogen, and the hydrides suppressed martensitic transformation. Theelectrolytically charged hydrogen can be easily released by heat treatment and the transformationoccurred again, which was verified by the DSC and XRD experiments.

Transformation, Deformation and Microstructure Characteristics of Ru_(50)Ta_(50) High Temperature Shape Memory Alloy

The basic martensitic transformation （MT） properties of Ru50Ta50 alloy, i.e. MT temperature （MTT）, temperature hysteresis （△T）, and MT heat （△H） 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 （Ms^1, Ms^2） and the temperature hysteresis （△T1, △T2） are 1047, 784 and 11, 14℃, respectively. No significant effect of aging treatment and thermal cycling on MTT and AT of Ru50Ta50 alloy were observed, but △H decreases slowly with increasing thermal cycles. The hardness and brittleness of Ru50Ta50 alloy are high. The deformation mode of RuTa alloys is twinning.

PHASE TRANSFORMATIONS IN RAPIDLY SOLIDIFIED TiNi SHAPE MEMORY ALLOYS

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应用阴阳锉跖趾关节成形治疗Freiberg病的临床研究

目的 探讨应用阴阳锉辅助进行跖趾关节成形配合间质填充治疗Freiberg病的临床疗效。方法 选取2019年8月至2023年9月郑州市骨科医院收治的30例Freiberg病患者。其中,男6例,女24例;年龄17~45岁,平均(26.5±6.8)岁。根据Smillie分期:Ⅲ期13例,Ⅳ期9例,Ⅴ期8例。均采用阴阳锉辅助进行跖趾关节成形配合间质填充治疗。术后采用AOFAS评分系统及跖趾关节屈伸活动度进行评价手术效果。结果 所有患者均获得随访,随访时间6~36个月,平均(26.5±13.9)个月。所有患者伤口均Ⅰ期愈合;AOFAS评分由术前(55.3±6.2)分提高到术后6个月的(90.8±5.9)分,差异有统计学意义(P<0.05),所有患者症状得到明显改变;跖趾关节活动度术前跖屈(20.3±5.3)°、背伸(15.2±5.6)°与术后6个月随访测量跖屈(18.9±5.1)°、背伸(14.1±5.2)°相比较,差异无统计学意义(P>0.05)。结论 采用阴阳锉辅助进行跖趾关节成形配合间质填充来治疗该疾病,该术式创伤小,操作简单,既减轻的疼痛症状,又保留了跖趾关节的外形及活动度,改善了患者的生活质量,是较为可靠的一种治疗方案,值得推广应用。

GRAIN SHAPE EFFECT IN SUPERPLASTIC DEFORMATION

The method controlling grain shape in TMT processing and the effect of grain shape on char- acteristic parameters in superplastic deformation were discussed.The accommodation velocity of grahl boundary sliding,which is the dominant mechanism in superplastic deformation,and the contribution of each mechanism to the total strain,as influenced by grain shape,were ana- lyzed.Grain shape has been shown to be an essential structural factor for superplasticity.Then an analysis was made about the effect of grain shape on the region transition strain rate so that a new concept,critical aspect for superplasticity,was worked out.These predictions were compared with the measured results in an Al-Zn-Mg alloy.

“两墙合一”深基坑工程设计与技术创新

北京CBD核心区某项目基坑深度36m,因受场地空间限制,采用“两墙合一”+内支撑支护体系,在实现基坑挡土、止水功能的同时完成了地下结构外墙施工。为提高工程质量和施工效率,针对地连墙与主体结构的连接、槽段接头处理方式、有限空间导墙结合近接建筑物预换撑等方面进行了技术创新,取得了较好的工程效果,可供类似工程参考。

热处理对石墨烯调控3D打印多孔钛组织与性能的影响

传统的多孔钛制备工艺存在缺陷,导致多孔钛材料的结构和性能难以重复和再现。本研究对选择性激光熔化(selective laser melting,SLM)成形的多孔纯钛与多孔石墨烯-钛(Gr-Ti)经500℃,30 min退火处理后,多孔纯钛与多孔Gr-Ti复合材料的物相均与SLM成型的多孔钛保持一致。多孔纯钛的组织由条纹状α’相转变为等轴α相,同时晶粒的各向异性消失;添加石墨烯后的多孔钛由条纹状α’相转变为等轴α相,生成的碳化钛弥散分布于钛基体中,且由于退火温度较低,基体中仍保留有石墨烯。热处理后多孔纯钛与多孔Gr-Ti显微维氏硬度均降低,多孔Gr-Ti热处理后抗压强度提高到345 MPa,比热处理前多孔钛的强度提升9.2%。热处理后多孔Gr-Ti材料耐腐蚀性能降低。

7×19构型NiTi形状记忆合金绞线超弹性试验研究

为充分发挥大直径NiTi形状记忆合金(SMA)绞线的超弹性性能,在常温下对单丝直径1.0 mm的7×19构型SMA绞线进行了循环拉伸试验;分析了热处理方案、应变幅值、循环次数、预训练和加载速率等因素对其超弹性的影响,得到了各因素下SMA绞线的残余应变、能量耗散、等效粘滞阻尼比、强度和刚度等力学参数变化规律。结果表明:针对本研究的7×19构型SMA绞线,400℃退火10 min的热处理方案下其相变应力和恢复率最高,热处理时间过长会造成这些特性严重退化;SMA绞线内部单丝变形和应力发展不均匀程度更高,滞回曲线无明显相变平台;恒定幅值拉伸下SMA绞线的初始弹性模量和极限应力变化相对较小,而相变平台高度、恢复率以及等效粘滞阻尼比退化较为明显;通过预训练的方式可以减轻SMA绞线的功能损伤,显著减小残余变形,提高可恢复能力;加载速率对SMA绞线的马氏体应力和屈服平台切线模量的影响较大,当加载速率超过1×10^(-2) s^(-1)后,滞回曲线对加载速率的变化不再敏感。试验结果可为7×19构型SMA绞线的应用提供数据支持。

热处理工艺对3种不同Cr系冷作模具钢热处理变形的影响

精冲模在服役过程中受较大的循环载荷导致的变形会增加其维修成本并缩短模具寿命。综合考量精密模具在热处理过程中产生的形变因素,相变引起的体积膨胀更受关注。设计出了一种新型“井”字型变形模块,研究了D2、DC53和7Cr5Mo2V 3种冷作模具钢在不同真空热处理工艺下相变引起的尺寸变化规律。结果表明:在1030℃淬火后,DC53钢的最大形变率约为0.65%;在210℃低温回火和520℃高温回火后,7Cr5Mo2V钢的最大形变率分别约为1.04%和1.81%。影响模具热处理变形的因素是残留奥氏体含量、二次碳化物析出的量和马氏体特征参数等。经210℃低温回火后,7Cr5Mo2V、D2和DC53钢的残留奥氏体体积分数分别为14.44%、13.21%和11.43%;520℃高温回火后,残留奥氏体体积分数均显著减少,分别为6.04%、3.39%和2.53%。

Ti_(53)Ni_(47)形状记忆合金的相变行为及其在模拟体液中的耐蚀性研究

对Ti_(53)Ni_(47)形状记忆合金进行不同温度的退火处理。采用差示扫描量热法(DSC)对其相变点进行测定,研究其相变行为。采用光学显微镜(OM)观察显微组织,利用X射线衍射仪(XRD)进行物相分析,采用Hank's溶液模拟人体体液环境,测试极化曲线,探讨热处理温度对显微组织及耐蚀性的影响。结果表明:不退火或经低温退火后,合金在-30~200℃冷却或加热时不发生相变。经高温退火,合金在20~200℃将发生相变,退火温度升高,转变容易。未退火和经300℃退火的合金室温相为B2相,而经400、500℃退火的合金室温相为B2和B19';合金内部存在黑色点状组织,其原子分数近似为Ti51Ni49。经退火处理,合金在模拟人体体液环境中的耐蚀性得到提升,但并非线性变化,呈一定的波动性。

基于“阴成形,阳化气”理论探讨肿瘤论治

“阴成形,阳化气”是对中医阴阳理论属性的高度概括,也是对肿瘤本质和病理机制的高度概括。通过总结近年国内研究者基于“阴成形,阳化气”理论在不同肿瘤论治方面的经验和成果,从而推断该理论对肿瘤的论治具有一定的指导意义,能提高肿瘤临床治疗效果,改善患者的生活质量,延长生存期。肿瘤形成是机体阳气受损而阴聚成形,是“阳化气”不及导致的“阴成形”太过。在现代中医临床诊疗中,运用“阴成形,阳化气”原理和理论基础,对肿瘤患者进行辨证施治,往往能取得良好效果。因此,未来临床上应重视“阴成形,阳化气”理论的运用,以指导肿瘤相关疾病的治疗与机制研究。