Phase transformation behaviors and shape memory effects of TiNiFeAl shape memory alloys

Measurements of electrical resistivity, X-ray diffraction, and tensile test at room temperature and ?196°C were performed to investigate the effects of Al addition substituting Ni on the phase transformation behaviors, the mechanical properties, and the shape memory effects of Ti50Ni47Fe2Al1 and Ti50Ni46.5Fe2.5Al1 alloys. It is found that 1at% Al addition dramatically decreases the martensitic start transformation temperature and expands the transformation temperature range of R-phase for TiNiFeAl alloys. The results of tensile test indicate that 1at% Al improves the yield strength of Ti50Ni47Fe2Al1 and Ti50Ni46.5Fe2.5Al1 alloys by 40% and 64%, but de- creases the plasticity to 11% and 12% from 26% and 27% respectively. Moreover, excellent shape memory effect of 6.6% and 7.5% were found in Ti50Ni47Fe2Al1 and Ti50Ni46.5Fe2.5Al1 alloys, which results from the stress-induced martensite transformation from the R-phase.     

制备方法对Ti50.2Ni29.8Cu20合金显微组织和相变行为的影响

采用常规铸造和快速凝固两种合金制备方法,分别制备出化学成分为Ti50.2Ni29.8Cu20的合金体材料和合金薄带,利用XRD(X射线衍射仪)、TEM(透射电子显微镜)、DSC(差示扫描量热仪)等手段研究这两种制备方法对Ti50.2Ni29.8Cu20合金的马氏体相变行为和显微组织方面的影响。实验结果表明,经500℃退火1h处理后,Ti50.2Ni29.8Cu20合金薄带中出现大量B19马氏体和少量Ti2Ni析出相,而固溶后的Ti50.2Ni29.8Cu20合金体材料只存在B19马氏体,同时相比于体材料,薄带的B19马氏体衍射峰强度减小及B19晶格常数a、b增大,而c减小;Ti50.2Ni29.8Cu20合金薄带的马氏体相变温度Ms比体材料的马氏体相变温度Ms低,且薄带的热滞△T也比体材料小。     

退火工艺对Ti50.2Ni29.8Cu20合金薄带中马氏体相变的影响

通过快速凝固法制备Ti50.2Ni29.8Cu20合金薄带,并利用XRD(X射线衍射仪)、DSC(差示扫描量热仪)、TEM(透射电子显微镜)等手段研究退火温度和退火时间对Ti50.2Ni29.8Cu20合金薄带马氏体相变的影响.结果表明,退火处理后Ti50.2Ni29.8Cu20合金薄带的室温相主要是B19马氏体和少量...     

26Cr2Ni4MoV钢淬火过程的三场耦合数值模拟

为定量分析大型锻件淬火加工过程中工艺参数的影响，应用非线性有限元，建立了淬火过程数值模拟的三场耦合模型，模型考虑了温度场、应力场、组织场及其耦合关系；热膨胀、塑性功生热、变温相变、相变潜热、应力诱导相变和相变膨胀及相变塑性等的效应，模拟了由锻件金属材料26Cr2Ni4MoV制成的空心圆筒工件在不同尺寸和工艺下的淬火过程，计算得到的冷却曲线及残余应力分布与实验结果一致，数值实验表明只有考虑应力诱导相变和相变塑性的作用，才能得到合理准确的结果。     

Effect of Sm-doping on the morphology and magnetic properties of radio frequency magnetron sputtered Ni-Mn-Ga films

Ni55.5Mn21Ga23.5 and Ni54Mn22Ga23Sm1 films were prepared by radio frequency (RF) magnetron sputtering. The effect of Sm do-pant on the morphologic and magnetic properties of Ni55.5Mn21Ga23.5 films was investigated. Sm doping can refine the particle size of the films from 100 to 60 nm, and further grain growth is not occurs even after annealing at 1073 K for 3.6 ks. Compared to Ni55.5Mn21Ga23.5 films, Sm-doped Ni54Mn22Ga23Sm1 films are easier to be magnetized and have a lower martensitic transformation temperature. In addition, the Curie temperature can also be adjusted, decreasing from 350 to 325 K after Sm doping. Martensitic transformation is not observed in the Sm-free films, which is close to the Curie temperature in the Sm-doped films, giving rise to the overlap of the structural and magnetic transi-tion temperatures.     

液态合金Ni3Al冷却过程中微观结构的转变

采用反映原子多体相互作用的FS势模型，通过分子动力学方法对液态Ni3Al的冷却过程进行了研究，考察了不同温度下Ni3Al结构变化特点.并给出了合金Ni3Al冷却过程微观结构转变的重要信息.对模拟的结果用热运动理论、从能量转换的角度给出了一些解释.     

CrMnB堆焊合金的空蚀行为

利用超声振荡空蚀实验设备研究了CrMnB堆焊合金的空蚀行为，实验结果表明：CrMnB堆焊合金抗空蚀性能显著高于0Cr13Ni5No马氏体不锈钢，堆焊合金中亚稳奥氏体在冲击力的作用下，诱发马氏体相变，提高堆焊合金表面的硬度和强度并吸收引起空蚀损伤的冲击能，是CrMnB堆焊合金具有很高抗空蚀性能的主要原因。     

复合硫杆菌对污泥重金属生物淋滤机制的影响

对污泥生物淋滤过程中各种重金属元素的形态变化情况进行了测定,借助重金属化学形态转化规律,间接判断污泥重金属生物淋滤的转化机制。试验结果显示,Cu、Ni、Cd的生物淋滤是以直接机制为主的,Zn的生物淋滤过程是以间接机制为主的,Cr、Pb的生物淋滤过程属于混合机制,但其混合机理是有差别的。     

钨对18Cr2Ni4WA钢相变,组织和性能的影响

利用１８Ｃｒ２Ｎｉ４ＷＡ和２０Ｃｒ２Ｎｉ４Ａ两种ＣｒＮｉ钢在成分、组织和性能上的差异，分析讨论了Ｗ对１８Ｃｒ２Ｎｉ４ＷＡ钢相变、组织和性能的影响结果表明，Ｗ显著抑制高温转变，在高温转变区等温３００ｈ也难以使其高温转变完成；Ｗ对中温转变的影响不像对高温转变影响那么显著，但使粒状组织转变右移，从而影响粒状贝氏体和粒状组织的相对量，并影响ＭＡ岛尺寸和Ｍ岛及Ａ岛的权重，增加残余奥氏体的稳定性和组织遗传倾向，从而影响其力学性能和工艺性能     

机械合金化制备Fe40Ni40Si5C15非晶合金

采用机械合金化方法制备了Fe-Ni-Si-C系的非晶态合金粉末,在球磨过程中对合金粉末进行取样,用XRD和DTA对不同球磨时间的Fe40Ni40Si5C15混合粉末进行了分析,发现合金粉末在球磨40 h开始部分非晶化,随球磨时间的增大晶粒尺寸减小。研究结果表明:在Fe-Ni-Si合金中加入C,可促进其形成非晶。通过机械合金化法,通过控制合理的球磨时间,在球磨70 h成功获得了Fe40Ni40Si5C15非晶粉末。     

Influences of composition and annealing on the martensitic transformation in Ni-Fe-Ga alloys

A series of Ni-Fe-Ga alloys near the prototype Heusler composition (X₂YZ) were prepared through arc-melting suction-casting method. The dependences of the transformation behavior on the alloy composition and annealing treatment were studied in detail by an optical microscope, X-ray diffraction, and differential scanning calorimeters methods. The experimental results show that the martensitic transformation temperatures increase almost linearly with increasing Ni content in all the NiFeGa alloys. Annealing the Ni_55.5Fe₁₈Ga_26.5 alloy at 100?C500 °C for 3 h and at 300 °C for 1?C10 h shifts the martensitic transformation start temperature by almost 20 °C to high temperature. The variations in the martensitic transformation temperatures in these alloys are discussed in terms of structural differences resulting from alloy composition and annealing treatment.     

The Deformation Behavior of TiNi Shape Memory Alloy under Axial Dynamic Compression

The deformation behavior of Ti-50.9at% Ni shape memory alloy under axial compression dynamic loads was investigated by an MTS 858Miru Bionic test machine. The alloy were aged at 500℃ for an hour before being machined into specimens. The compression experiments were conducted at 20℃ and the variety of dynomic loads were controlled by the strain rate, which was 3mm/min, 15mm/min, 30mm/min and 50mm/min, respectively. The experimental results indicate that in the case of 3mm/min. stress-induced martensitic transformation occurs at about 350 MPa when loading and reverse transformation at about 200 MPa when unloading, during which the aged Ti-50.9at% Ni alloy shows the recoverable nonlinear pseudoelastic strain of 4.3%with the residual strain of 1.2% reserved. With the strain rate increasing, the area encloses by loading-curve and unloading-curve, i. e stress ( strain ) hysteresis becomes smaller and smaller and the residual strain also decreases, while critical stress for inducing martensitic transformation rises. At a higher strain rate the alloy exhibits linear-like pseudoelasticity, which is up to 4.5％ .     

pH对掺杂Zn纳米Ni(OH)2电化学性能的影响

为研究pH值对掺锌氢氧化镍电化学性能的影响,采用沉淀转化法在不同pH下制备出掺杂Zn的纳米Ni(OH)₂. 利用XRD和TEM对材料的结构和微观形貌进行分析,利用循环伏安技术和恒流充放电技术对材料的电化学性能进行研究. 结果表明,pH=10时制备的材料是α型纳米Ni(OH)₂,随着pH的增大,材料逐渐变成α-Ni(OH)₂和β-Ni(OH)₂的混合物,且材料的团聚逐渐严重. pH的变化对材料的电化学性能影响明显. 随着pH的增加,材料的质子扩散系数增大;与pH=10时制备的材料相比,pH=12时制备的材料02C和3C放电比容量分别提高了20％和27％.     

18Cr_2Ni_4WA钢中的C—Cr,C—Ni,C—W偏聚对固态相变的影响

从“余氏理论”出发.对18Cr_2Ni_4WA钢的价电子结构进行了计算,应用“固溶液微观不均匀性理论”,在构成材料原子的价电子结构的深度上,提出了C—Cr,C—Ni,C—W偏聚,并讨论了这种偏聚对18Cr_2Ni_4WA钢的相变动力学与组织的形态的影响。     

大豆甾醇的微生物降解及酶抑制剂的选择

测定了诺卡氏菌、分枝杆菌和节杆菌对大豆甾醇的降解能力及Ｎｉ＾２＋、Ｃｏ＾２＋，Ｍｎ＾２＋，α，α′－联吡啶、邻菲罗啉等酶抑制剂对△＾１，４－雄甾二烯－３，１７－二酮积累的影响。实验结果表明，节杆菌Ａ－６在６０＊１０＾－６硫酸镍存在下，使大豆甾醇的转化率达７０％以上，ＡＤＤ产率达３０％左右。     

Simulation of transformation mechanism of martensites in Ni62.5Al37.5 alloy

Thermally induced L1₀ martensitic transformation in an ordered B2 Ni_62.5 Al_37.5 alloy has been studied by using molecular dynamics computer simulations and embedded atorn method (EAM) potential. The nucleation mechanism and growth process of martensites were investigated by analyzing the difference between the lattice vibrational properties, strain distributions in transforming and non-transforming regions. The effect of the difference between vibrational properties of Ni and Al atoms on the transformation was discussed.     

0Cr18Ni9不锈钢焊接温度场的数值仿真

基于有限元软件SYSWELD对不锈钢0Cr18Ni9平板TIG焊的温度场进行三维动态模拟,得出了瞬态温度场分布图和特征点的热循环曲线,同时也得出了焊缝上任一点的温度变化与相变的关系.与文献资料比较表明,所建立的数值模拟仿真模型可以较好的模拟焊接温度场,为研究焊接过程中的应力应变和减少焊接应力与变形提供了参考依据.     

TEM study of transformation units and the growth mechanism of bainite

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Simulation of transformation mechanism of martensites in Ni_(62.5)Al_(37.5) alloy

Ｔｈｅｓｔｕｄｙｏｎｍａｒｔｅｎｓｉｔｉｃｔｒａｎｓｆｏｒｍａｔｉｏｎｉｓｔｈｅｏｒｅｔｉｃａｌｌｙａｎｄｐｒａｃｔｉｃａｌｌｙｉｍｐｏｒｔａｎｔ.Ｉｔｉｓｖｅｒｙｄｉｆｆｉｃｕｌｔｔｏｏｂｓｅｒｖｅｔｈｅｔｒａｎｓｆｏｒｍａｔｉｏｎｐｒｏｃｅｓｓｂｙｍｅａｎｓｏｆｅｘｐｅｒｉｍｅｎｔｓｂｅｃａｕｓｅｏｆｔｈｅｖｅｒｙｆａｓｔｓｐｅｅｄｏｆｔｒａｎｓｆｏｒｍａｔｉｏｎｓ,ｗｈｉｃｈｍａｋｅｓｑｕａｎｔｉｔａｔｉｖｅｓｔｕｄｙｄｉｆｆｉｃｕｌｔａｎｄｔｈｅｍｅｃｈａｎｉｓｍｏｆｎｕｃｌｅａｔｉｏｎａ…     

Ni-SiC复合镀层的热稳定性和耐蚀性

用电沉积方法在钢上获得Ni SiC复合镀层 ,研究了Ni SiC复合镀层在 85 0℃的热稳定性及通过极化曲线的测定 ,对钢基体、Ni层、Ni SiC层耐蚀性进行比较 .结果表明 ,SiC在 85 0℃加热保温半小时时SiC不分解 ,Ni SiC复合镀层的耐蚀性最好 ,Ni镀层次之 ,钢基体最差 .