固溶态Ti（50＋x）Pd30Ni（20—x）合金中的相变特征

Ti(50 x)Pd30Ni(20-x)合金在固溶处理之后存在2次相变，使用DSC，XRD，DMTA以及TEM等手段研究了这种相变，结果表明，低温马氏体为单斜的B19'相，而高温母相则为体心立方的B2相，在相变过程中点阵的切变以正交的B19马氏体相作为过渡。低温马氏体的弹性模量比高温奥氏体的弹性模量高10GPa。随着频率减小，阻尼增大。在较高的频率下，弹性模量曲线和阻尼曲线对于过渡相的存在反映不明显，室温下马氏体为细狭的板条状，当温度达773K时，合金中有明显的析出物产生。     

MARTENSITE TRANSFORMATION OF A TiNiCu ALLOY

ＭＡＲＴＥＮＳＩＴＥＴＲＡＮＳＦＯＲＭＡＴＩＯＮＯＦＡＴｉＮｉＣｕＡＬＬＯＹ￥Ｚｈａｎｇ，Ｙｉ；Ｊｉｎ，Ｊｉａｌｉｎｇ；Ｊｉ，Ｚｈｉｑｉａｎｇ（ＳｈａｎｇｈａｉＩｒｏｎａｎｄＳｔｅｅｌＲｅｓｅａｒｃｈＩｎｓｔｉｔｕｔｅ，Ｓｈａｎｇｈａｉ２００９４０）...     

时效处理对TiNiCr形状记忆合金相变的影响

利用差示扫描量热仪(DSC)、扫描电镜(SEM)和D/max2500PC全自动X射线衍射仪研究了不同时效处理制度下TiNiCr合金相变温度的变化规律.结果表明,该合金随着时效温度增加,逆马氏体相变点As、Af上升,但当时效温度高于700℃时,相变点As、Af降低.该合金在冷却过程中经历了B2→R→B19′两阶段一级相变.通过SEM和XRD衍射研究表明,该合金经时效处理产生了Ti3Ni4析出相诱发了R相变.     

Ti49.4Ni50.6超弹性弹簧的相变和形变特性

用示差扫描量热仪、拉伸实验和应力-应变循环实验系统研究了退火温度、变形温度以及热循环和室温应力-应变循环对Ti49．4Ni50．6超弹性(SE)弹簧的相变和形变特性的影响。冷加工加中温退火态Ti49．4Ni50．6合金冷却→←加热时的相变类型为母相B2→←R相→←马氏体B19′。随退火温度升高，马氏体转变温度升高，R相转变温度降低。623-773K退火态Ti49．4Ni50．6弹簧室温下可获得SE特性，随变形温度升高，SE弹簧剐度增加；当退火温度超过823K后，SE持性变差。热循环时SE弹簧的切变量取值越小，其应变恢复率越高。预循环训练可增强SE的稳定性。     

Martensitic transformation behavior of Ti–Ni–Ag alloys

Microstructures and martensitic transformation behavior of Ti–Ni–Ag alloys prepared by arc melting were investigated by means of scanning electron microscopy (SEM), electron probe micro analysis (EPMA), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and thermal cycling tests under constant load. Ti–Ni–Ag alloys consisted of Ti–Ni–Ag matrices, Ti₂Ni and TiAg phases. Ti–Ni–Ag matrices contained 0.27–0.52 at.% of solute Ag atoms depending on alloy compositions. The B2–B19′ transformation occurred in Ti–50.1Ni–0.7Ag, Ti–49.2Ni–0.9Ag, Ti–49.2Ni–0.6Ag and Ti–49.0Ni–0.7Ag alloys, while the B2-R-B19′ transformation did in Ti–47.5Ni–1.3Ag and Ti–44.4Ni–1.1Ag alloys. Thermo-mechanical treatment separated the B2-R from the R–B19′ transformation clearly and improved shape recovery by increasing the critical stress for slip deformation in a Ti–50.0Ni–0.7Ag alloy.     

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%.     

TRANSFORMATION BEHAVIOR OF Ti50-x/2Ni50-x/2Cux ALLOYS

1.IntroductionIt is known that transformation behavior of Ti50Ni50-xCux shape memory alloys depends on the Cucontent[1-3].When the substitution of Cu for Ni is less than5at.%,the alloy transforms similar to that ofthe equiatomic Ti-Ni alloy,i.e.,from cubic(B2)to monoclinic(B19′).When the substitution of Cureaches10at.%,the alloy transforms in two stages,i.e.,from cubic(B2)to orthorhombic(B19),and thenfrom orthorhombic to monoclinic(B19′).By further substitution exceeding20at.%,the allo…     

第二相对等径弯角挤压处理TiNi合金和Ti-Mo基合金力学性能及马氏体转变的影响

借助ECAP技术对TiNi合金和Ti-Mo基记忆合金在673~773K进行挤压处理,挤压路径为Bc,以获得超细晶组织,从而增强母相的强度,改进材料的性能。研究热力学稳定相及亚稳相对这两种合金的力学性能和马氏体转变的影响。结果表明,对于富钛TiNi合金,热力学稳定相Ti2Ni对马氏体转变及超弹性没有影响,而稳定相α相则可造成Ti-Mo-Nb-V-Al塑性降低。亚稳Ti3Ni4相对富镍TiNi合金的R相变、马氏体转变及超弹性有很大影响。并对第二相对TiNi合金和Ti-Mo基合金力学性能、马氏体转变的影响进行分析。     

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.     

Ti含量对Ni53Mn23.5Ga23.5-xTix铁磁性形状记忆合金组织和性能的影响

采用光学显微镜、示差扫描热分析、交流磁化率测试和室温压缩试验等方法系统研究Ti含量对Ni53Mn23.5Ga23.5-xTix (x=0, 0.5, 2, 3.5, 8, 15)合金的显微组织、相变行为、力学行为和磁学特性的影响规律。结果表明：Ti元素在合金中的极限固溶度低于15%;随着Ti含量的增加,合金的相变温度和断裂强度及断裂应变先逐渐增加后降低,其断裂方式由沿晶断裂转变为穿晶断裂再到沿晶断裂;而合金的居里温度随Ti含量的增加逐渐降低     

Sn替代Si和B对Ti50Ni22Cu18Al4Si4B2合金机械研磨非晶化的促进作用

采用Xn替代Ti50Ni22Cu18Al4Si4B2合金中的Si和B1形成Ti50Ni22Cu18Al4Snx(Si0．67B0．33)6-x(x=0，3，6)系列合金．所有的预制合金碎屑经过机械研磨均发生非晶化转变．随着合金中Sn含量的增加，球磨产物中转变未尽的晶体相α-Ti含量减少．由Sn完全替代Si和B的Ti50Ni22Cu18Al4Sn6合金，机械研磨可形成与熔体急冷几乎相同的单一均匀非晶相，过冷液态温度区间可达到66K．     

Age-induced multi-stage transformation in a Ni-rich NiTiHf alloy

Abnormal multi-stage transformations have already been studied in binary Ni-rich NiTi alloys. In this research, this kind of transformation was investigated in a low supersaturated Ni-rich ternary NiTiHf high-temperature shape memory alloy by aging at intermediate temperatures for various durations. Meticulous examinations of the results of differential scanning calorimetry tests demonstrated the heterogeneous precipitation of (Ti,Hf)₃Ni₄ particles and the three-stage transformation (one-stage R and two-stage B19′) in the aged alloy. Aging provided a significant rise in transformation temperatures (TTs) until they reached their equilibrium states, corresponding to the equilibrium Ni content at each aging temperature. Equilibrium TTs were higher when aging was performed at a lower temperature. The remarkable increase in TTs was compared with those in aged Ni-rich NiTi alloys, and discussed based on the variation in valence electron concentration. A model was also proposed for the microstructural evolution during aging. Furthermore, aging provided enhanced hardness and strain recovery for the alloy. In particular, aging at a lower temperature resulted in a considerable improvement in hardness and shape recovery, which was discussed based on the microstructural changes in the aged alloy. Equilibrium Ni content at each aging temperature proved to be a crucial parameter in controlling the alloy properties, even in heterogeneous precipitations.     

球磨表面包覆对镁基贮氢合金电化学性能的影响

表面包覆是一种表面改性方法,对于提高贮氢合金表面活性,防止氧化和抑制容量衰退有较积极的作用。探索了以球磨方法对二元非晶合金Mg50Ni50和三元非晶合金Mg(50-x)TixNi50(x=5,10,15)进行表面包覆的工艺及其对合金电极充放电循环稳定性的影响。结果表明：Y,Al,Ni等包覆元素皆可在一定程度上延缓非晶合金Mg50Ni50较快的循环容量衰退,而且Ni对Mg(50-x)TixNi50(x=5,10,15)合金的包覆可有效地提高其循环稳定性。     

Ti0.9Zr0.2Mn（1.8—x）MxV0.2（M=Ni,Cr;x=0,0.2）合金的贮氢性能

研究了Ti0.9Zr0.2Mn(1.8-x)MxV0.2(M=Ni,Cr;x=0,0.2)合金的晶体结构与贮氢性能。结果表明,Ti0.9Zr0.2Mn1.6Ni0.2V0.2和Ti0.9Zr0.2Mn1.6Cr0.2V0.2的贮氢量达到240mL/g。合金的主相均为C14 Laves相,镍,铬的取代使点阵常数和晶胞体积增大,P－C－T曲线的滞后降低,压力平台的倾斜度增加。     

Ti-(Cu,Ni)-Sn合金形成金属玻璃的成分优化及其相关联的共晶反应

采用“3D法”, 系统地研究了Ti-(Cu1-xNix)-Sn(0.20≤x≤0.30, 原子分数, 下同) 四元合金的玻璃 形成能力对成分变化的依赖性. 确定玻璃形成能力最佳的合金为Ti38Cu37.8Ni16.2Sn8,Cu模吸铸形成金属玻璃 棒材的临界直径接近1 mm.该金属玻璃的过冷液态温度区间宽度ΔTx为56 K, 约化玻璃转变温度T rg为0.57. 对电弧熔炼Ti38Cu37.8Ni16.2Sn8合金微观结构的研究表明,合金熔体的凝固主要经历伪二元共晶反应:L→ Ti5Sn3Cu+TiCuNi.     

Phase transformation behavior of Ti49Ni49.5Fe1V0.5 and Ti48Ni48.5Fe1V2.5 alloys after different heat treatments简

The effects of heat treatments on the phase transformation behavior of Ti49 Ni49.5 Fe1 V0.5 and Ti48 Ni48.5 Fe1 V2.5 alloys were investigated. The results indicate that the alloys subjected to different heat treatments have B2 structure at room temperature. All the specimens exhibit a twostage B2→R→B190martensitic transformation on cooling, but a B190→B2 one-stage reverse martensitic transformation on heating except aged A1 alloy, which undergoes an abnormal two-stage transformation upon heating. The phase transformation temperatures are affected by heat treatments and V content, which can be attributed to the variation of the second-phase particles content in the matrix.     

Martensitic transformation and magnetic properties of Ti-doped NiCoMnSn shape memory alloy

Martensitic transformation, microstructure, and magnetic properties of Ti-doped Ni43-xTixCo7Mn43Sn7（at%）（x = 0, 0.5, 1.0, 2.0, and 4.0） shape memory alloys were investigated. The results show that transformation temperatures of Ni43Co7Mn43Sn7 can be efficiently adjusted by the substitution of Ti for Ni. For example, the martensitic transformation starting temperature（Ms） is reduced by about 278 K with 4 at% addition of Ti. Room temperature microstructure evolves from single tetragonal martensite for the Ti-free alloy to dual phases（tetragonal martensite ＋ second phase） with 0.5 at%, 1.0 at%, and2.0 at% addition of Ti to dual phases（cubic austenite ＋ second phase） for 4.0 at% Ti-doped alloy. The mechanical properties can be obviously improved by adding an appropriate amount of Ti. A noteworthy point is that magnetic-field-induced reverse transformation is observed in Ni39Ti4Co7Mn43Sn7 alloy.     

TEM study of structural and microstructural characteristics of a precipitate phase in Ni-rich Ni–Ti–Hf and Ni–Ti–Zr shape memory alloys

The precipitates formed after suitable thermal treatments in seven Ni-rich Ni–Ti–Hf and Ni–Ti–Zr high-temperature shape memory alloys have been investigated by conventional and high-resolution transmission electron microscopy. In both ternary systems, the precipitate coarsening kinetics become faster as the Ni and ternary element contents (Hf or Zr) of the bulk alloy are increased, in agreement with the precipitate composition measured by energy-dispersive X-ray microanalysis. The precipitate structure has been found to be the same in both Hf- and Zr-containing ternary alloys, and determined to be a superstructure of the B2 austenite phase, which arises from a recombination of the Hf/Zr and Ti atoms in their sublattice. Two different structural models for the precipitate phase were optimized using density functional theory methods. These calculations indicate that the energetics of the structure are not very sensitive to the atomic configuration of the Ti–Hf/Zr planes, thus significant configurational disorder due to entropic effects can be envisaged at high temperatures. The precipitates are fully coherent with the austenite B2 matrix; however, upon martensitic transformation, they lose some coherency with the B19′ matrix as a result of the transformation shear process in the surrounding matrix. The strain accommodation around the particles is much easier in the Ni–Ti–Zr-containing alloys than in the Ni–Ti–Hf system, which correlates well with the lower transformation strain and stiffness predicted for the Ni–Ti–Zr alloys. The B19′ martensite twinning modes observed in the studied Ni-rich ternary alloys are not changed by the new precipitated phase, being equivalent to those previously reported in Ni-poor ternary alloys.     

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。     

Mg100—xNix（x=7—79）合金机械合金化制备研究

研究了不同成分的Ｍｇ－Ｎｉ合金（Ｍｇ１００－ｘＮｉｘ,ｘ＝７－７９）的机械合金化制备。实验结果表明,在机械球磨的条件下,其相变过程和相变产物与熔炼合金有很大差异。在所研究的１０个成分中,当ｘ＝７,１２时,球磨产物为Ｍｇ２Ｎｉ金属间化合物与晶态Ｍｇ的混合相;当ｘ＝１８,２５时,则形成单相的纳米晶Ｍｇ２Ｎｉ;当ｘ＝３３４,４３,５５,６７,７０时,合金粉末发生非晶化转变,形成单一的非晶相,且对于不同的