Ti50＋x Pd30Ni20—x合金的相变温度

使用热分析和高温X射线研究了Ti50-xPd30Ni20-x合金相变温度的变化情况,发现当Ti的原子分数偏离50%时,合金的相变温度随Ti成分的升高而降低,处于固溶处理的合金的相变温度最高,合金经过轧制及回复处理后,相变温度会降低。分析认为,这与合金内的缺陷、内应力和析出物密切相关。     

Ti50＋xPd30Ni20—x高温形状记忆合金的弹性行为

制备了三种Ti50 xPd30Ni20-x高温形状记忆合金,使用热分析测试了合金的相变温度,发现当Ti原子分数偏离50％时,合金的相变温度随Ti成分的升高而降低,并对这种合金的力学性能进行了测试,合金在奥氏体转变结束温度以上变形仍具有形状记忆效应,应力诱发的马氏体在应力去除后不能恢复到奥氏体,研究了这种合金在不同的重复加载条件下的弹性行为,实验表明,弹性回线的形状特征与加载历程有关,在奥氏体转变结束温度附近加载可以获得完全的线性伪弹性;而对于处于稳定单相的试样,在重复加载的条件下也可以获得弹性滞后回线。     

Ni—Ti合金时效早期相变规律的研究

通过ＴＥＭ分析对Ｎｉ－１０％Ｔｉ（％，质量分数，不同）合金时效早期相变过程的研究表明Ｎ１－１００％Ｔｉ合金过饱和固溶体先通过调幅分解机理分解为贫、富溶质区；随后富溶质区发生有序化，最后形成Ｌ１２型有序相Ｎｉ３Ｔｉ。同时发现，淬冷抑制了该合金固溶体的相分解过程。Ｎｉ－Ｔｉ合金时效相变过程中存在调幅分民有序化两种失稳模式共存现象。     

固溶时效态Ti-Ni合金相变行为与Ni含量的关系

固溶淬火态Ti100-xNix合金中，x=40．0—49．O时，合金的马氏体相变(MT)温度(TM)、热滞(△TM)不变，相变热(△HM)升高；x=49．0—52．0时，合金的TM和△HM急剧下降，△TM急剧升高；x=52．0—56．0时，合金的TM和△HM升高，△TM降低；x=56．0—70．0时，合金的TM和△TM变化不大，△HM下降．673K时效态Ti1oo—xNix合金中，x=40．0—50．0时，合金发生MT，不存在时效效应；x=50．5—70．0时，合金既发生MT又发生R相相变(RT)且具有时效效应．随时效时间(tA)延长，TM和△HM先下降后上升，△TM下降．TR随x增加保持不变，随tA延长而升高．△TR对x和tA不敏感．△HR对z和TA都十分敏感．x=40．0—50．0和x=50．5—70．0合金的室温组织分别为M TiNi2和A(母相) 析出物．随x增加或tA延长，x=50．5—70．0的合金中析出物数量增多．     

Ti50+xPd30Ni20-x合金的相变温度

使用热分析和高温X射线研究了Ti     

Ni50Ti30Zr20与Ni50Ti50合金摩擦磨损性能对比研究

目的以Ni_(50)Ti_(50)合金为参照物,研究Ni_(50)Ti_(30)Zr_(20)合金的摩擦磨损性能。方法采用非自耗真空电弧熔炼炉炼制Ni_(50)Ti_(30)Zr_(20)合金,在合金铸锭上切取样品,以Ni_(50)Ti_(50)合金为对比样品,通过能谱测试(EDS)、X射线衍射(XRD)、显微硬度(HV)测试、摩擦磨损测试、扫描电镜测试(SEM)和3D形貌测试,分别评价Ni_(50)Ti_(30)Zr_(20)合金与Ni_(50)Ti_(50)合金的成分、相组成、显微硬度、耐磨性、磨痕形貌和磨损体积。结果XRD结果显示,Ni_(50)Ti_(50)和Ni_(50)Ti_(30)Zr_(20)合金室温分别由B2奥氏体和B19’马氏体相组成。显微硬度测试结果表明,Ni_(50)Ti_(30)Zr_(20)和Ni_(50)Ti_(50)合金的显微硬度值分别为(381.64±7.32)HV和(230.58±6.74)HV。从形貌图可以看出,两种合金磨损后,磨痕形貌主要由剥层组成。从磨痕能谱分析得出,摩擦实验后,样品表面O和Si元素含量明显增加。根据摩擦系数曲线和磨痕三维形貌图发现,同样载荷下,Ni_(50)Ti_(30)Zr_(20)合金的摩擦系数和磨损体积均小于Ni_(50)Ti_(50)合金,在载荷为20 N时,Ni_(50)Ti_(30)Zr_(20)合金的磨损体积为0.078 mm~3,Ni_(50)Ti_(50)合金的磨损体积为0.084 mm~3。结论Ni_(50)Ti_(30)Zr_(20)与Ni_(50)Ti_(50)合金的磨损机制均为疲劳磨损,两种合金在摩擦实验过程中均会发生氧化,同时磨球会有部分剥落到合金磨痕剥层中。Ni_(50)Ti_(30)Zr_(20)合金的耐磨性优于Ni_(50)Ti_(50)合金。     

Ti_(50+x)Pd_(30)Ni_(20-x)高温形状记忆合金的弹性行为

制备了三种 Ｔｉ５０＋ｘＰｄ３０Ｎｉ２０－ｘ高温形状记忆合金,使用热分析测试了合金的相变温度发现当 Ｔｉ的原子分数偏离５０％时,合金的相变温度随 Ｔｉ成分的升高而降低,并对这种合金的力学性能进行了测试．合金在奥氏体转变结束温度以上变形仍具有形状记忆效应,应力诱发的马氏体在应力去除后不能恢复到奥氏体研究了这种合金在不同的重复加载条件下的弹性行为,实验表明,弹性回线的形状特征与加载历程有关在奥氏体转变结束温度附近加载可以获得完全的线性伪弹性;而对于处于稳定单相的试样,在重复加载的条件下也可以获得弹性滞后回线     

Transformation behavior and shape memory effect of Ti50-xNi48Fe2Nbx alloys by aging treatment

The influence of aging treatment on transformation behavior and shape memory of the Ti50-xNi48Fe2Nbx(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(Ms,Mf,Mp,As,Af,and Ap)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.     

Transformation Behavior of Ti50-x/2Ni50-x/2Cux alloys

Phase transformation behavior of Ti50-x/2Ni50-x/2Cux (x=2, 5, 15) alloys was investigated using differential scanning calorimetry (DSC). The results show that Ti50-x/2Ni50-x/2Cux alloys undergo a two-stage martensitic transformation on cooling and transform reversely in one stage on heating when treated at 823K for 5 hours. Heat treatment has no effect on the transformation behavior of Ti49Ni49Cu2 alloy but does influence that of Ti47.5Ni47.5Cu5 alloy and Ti42.5Ni42.5Cu15 alloy. Effect of heat treatment is related with precipitation of CuNiTi phase. The maximum recoverable elongation of Ti49Ni49Cu2 wire is about 6%.     

Ni52Mn21+xGa27-x(x=0-5)磁性形状记忆合金的相变

研究了非化学计量成分的多晶Ni52Mn21+xGa27-x(x=0-5)系列合金的热弹性马氏体相变和磁相变.合金的马氏体相变温度Ms随Mn含量的增加而升高,当x＞4时,Ms已经升高到室温以上,而马氏体相变滞后△T随z的增大而减小;合金的磁相变温度TC随z增加而升高,但变化范围不大,在z＞2后,Tc保持在348 K左右.实验获得了一种具有实用前景的合金成分--Ni52Mn25Ga23合金,其马氏体相变温度在室温以上,相变滞后仅为5 K.     

Martensitic transformation of Ti50Ni30Cu20 alloy prepared by powder metallurgy

Phase transformation behavior of Ti50Ni30Cu20 shape memory alloys prepared by powder metallurgy is analyzed with respect to the duration of mechanical alloying. The processed blends were studied by differential scanning calorimetry and room temperature X-ray diffraction. The martensitic transformations evidenced by thermal scans are discussed in correlation with the relative phase content obtained from the refinement of the X-ray diffraction patterns.     

Stress-induced martensitic transformation in （Ni47Ti44）100-xNbx shape memory alloys with wide hysteresis

The effect of deformation via stress-induced martensitic transformation on the reverse transformation behavior of the （Ni47Ti44）100-xNbx （x=3, 9, 15, 20, 30, mole fraction, %） shape memory alloys was investigated in detail by differential scanning calorimetry （DSC） after performing cryogenic tensile tests at a temperature of Ms＋30 ℃. The results show that Nb-content has obvious effect on the process of stress-induced martensitic transformation. It is also observed that the stress-induced martensite is stabilized relative to the thermally-induced martensite （TIM） formed on cooling, and Nb-content in Ni-Ti-Nb alloy has great influence on the reverse transformation start temperature and transformation temperature hysteresis of stress-induced martensite（SIM）. The mechanism of wide transformation temperature hysteresis was fully explained based on the microscopic structure and the distribution of the elastic strain energy of （Ni47Ti44）100-xNbx alloys.     

Ni52Mn23+xSn25-x(x=0,1,2)合金的磁性

利用X射线衍射和振动样品磁强计研究了Ni52Mn23 xSn25-x(x=0,1,2)合金的结构和磁性.结果表明,合金为铁磁性形状记忆合金.奥氏体具有强的铁磁性,而马氏体表现为顺磁或反铁磁性.磁化曲线表现出明显的磁场诱导马氏体相变行为.Sn含量对居里温度影响十分显著,而对马氏体相变温度影响很小.合金马氏体相变过程的温度范围很窄,约在5K以内.     

A wide temperature window for the magnetostructural transformation in Mn50Ni50-x-ySnxCoy alloys

In order to open a wide temperature window for a magnetostructural transformation, Sn–Co co-doping was explored in the Mn₅₀Ni₅₀ alloy. The experimental results show that doping with Sn and doping with Co have different effects on the martensitic and austenitic structures, the martensitic transformation, the thermal hysteresis and the magnetic properties of the martensitic and austenitic phases. By tuning the Sn and Co content in Mn₅₀Ni_50−x−ySn_xCo_y from x = 11, y = 0 to x = 6, y = 14, the martensitic transformation temperature, T_m, could be adjusted over the range from 99 K to 450 K, with the condition that T_m remains lower than the Curie temperature of the austenitic phase, Tc^a, which varied from 288 K to 565 K. Thus, a 351 K temperature window for the magnetostructural transformation was established and a series of ferromagnetic shape memory alloys was identified.