Effect of Ni content on the weldability of middle-chromium hyperpure ferritic stainless steels 00Cr21Ti

Excellent weldability substantially contributes to the intrinsic quality of steels,while appropriate chemical composition plays a primary role in the essential weldability of steels.The poor weldability of ferritic stainless steels could be improved through modification with minor alloy elements while minimally increasing the cost.Therefore,studying the effect of minor alloy elements on the weldability of steels is of considerable importance.In this study,several steels of middle-chromium hyperpure ferritic stainless 00Cr21Ti with different Ni content(0.3%,0.5%,0.8%,and 1.0%)were developed,and their weldabilities of butt joint samples welded using the metal inert gas welding process,including the influence of welded joints on the microstructure,tensile performance,corrosion resistance,and fatigue property,were investigated.Results show that the steels with w(Ni)≥0.8%exhibit excellent mechanical properties compared with those with low-Ni content steels,further,their impact toughness at normal atmospheric temperature meets the industrial application standard and the fatigue property is similar to that of 304 austenitic stainless steel.Moreover,results show that the corrosion resistance of all the samples is almost at the same level.The results acquired in this study are supposed to be useful for the optimization of the chemical composition of stainless steels aiming to improve weldability.

Effects of Ni content on the cast and solid-solution microstructures of Cu-0.4wt% Be alloys

The effects of Ni content（0–2.1wt%）on the cast and solid-solution microstructures of Cu-0.4wt%Be alloys were investigated,and the corresponding mechanisms of influence were analyzed.The results show that the amount of precipitated phase increases in the cast alloys with increasing Ni content.When the Ni content is 0.45wt%or 0.98wt%,needle-like Be_（21）Ni_5 phases form in the grains and are mainly distributed in the interdendritic regions.When the Ni content is 1.5wt%or greater,a large number of needle-like precipitates form in the grains and chain-like Be_（21）Ni_5 and Be Ni precipitates form along the grain boundaries.The addition of Ni can substantially refine the cast and solid-solution microstructures of Cu-0.4wt%Be alloys.The hindering effects of both the dissolution of Ni into the matrix and the formation of Be–Ni precipitates on grain-boundary migration are mainly responsible for refining the cast and solid-solution microstructures of Cu-0.4wt%Be alloys.Higher Ni contents result in finer microstructures;however,given the precipitation characteristics of Be–Ni phases and their dissolution into the matrix during the solid-solution treatment,the upper limit of the Ni content is 1.5wt%–2.1wt%.

Role of Ni content in improvement of corrosion resistance of Zn-Ni alloy in 3.5% Na Cl solution. Part I: Polarization and impedance studies

Zn plays an important role in the protection of iron and steel from corrosion in sea water, and the alloying of Zn and Ni can improve its corrosion resistance. The corrosion behavior of Zn？Ni alloys in synthetic sea water （3.5% NaCl, mass fraction） was studied using Tafel plot and electrochemical impedance spectroscopy （EIS） techniques. The corrosion resistance of the investigated alloys with various Ni contents （0.5%？10%, mass fraction） was compared with that of Zn. The results show that the corrosion resistance of Zn？Ni alloys （except 0.5% Ni） is superior to that of Zn. The 10% Ni gives the highest corrosion resistance due to the formation ofγ-Zn3Ni withγ-ZnNi phases in the alloy. In the case of alloy I （0.5% Ni）, it exhibits a higher corrosion rate （less corrosion resistance） than Zn.

Crystallization Kinetics of NiTi Films with Different Ni Contents

Three kinds of NiTi films with different Ni contents were prepared by DC magnetron sputtering. The crystallization kinetics of amorphous films was determined by using non-isothermal single- scan techniques. The results show that the activation energy of crystallization of Ni-rich NiTi film(Ni 51.10 at. pct, Ti 48.90 at. pct) is 715 kJ/mol; while that of Ti-rich films are similar: one is 445 kJ/mol (Ni 46.74 at. pct. Ti 53.26 at. pct), the other is 418 kJ/mol (Ni 43.21 at. pct, Ti 56.7g at. pct), which i5 lower than Ni-rich film. The Avrami parameter n of different films are 0.92 and 0.74 for Ni-rich film and Ti-rich films, respectively. The difference of kinetic parameters for NiTi films with various Ni contents implies that the crystallization behaviors of these films are distinct, which is confirmed by the calculated isothermal kinetics at different temperatures. The thorough research on this phenomenon is in progress.

Ni元素质量分数对65Mn钢木工圆锯片性能的影响

高质量、高效率的木材切削工艺对于提高木材资源的利用率以及提升木质产品的品质具有重要意义。目前,木工圆锯片常用钢材65Mn存在硬度和抗拉强度等力学性能欠佳的问题,为此通过添加镍(Ni)元素对65Mn钢进行改性。采用原料熔炼、浇筑试棒、锻造加工以及热处理等步骤制备Ni改性65Mn钢,并对改性前后的65Mn钢进行显微硬度、冲击韧性和拉伸强度测试。同时运用金相显微镜(metallographic)及扫描电镜(SEM)剖析65Mn钢改性前后的组织构造差异。研究结果表明,1)添加Ni元素后,65Mn钢回火后的组织由回火屈氏体改变为淬火马氏体与回火马氏体的混合体,且当Ni元素质量分数达到0.9%时,出现残余奥氏体;2)在相同热处理工艺条件下,Ni元素对材料的硬度和抗拉强度的影响均呈现出先增大后降低的趋势,冲击韧性较未改性的65Mn钢有所降低。其中,添加质量分数为0.7%Ni元素的65Mn钢的硬度和抗拉强度最优,较未改性的65Mn钢分别增加了10.18%、35.40%(室温)。研究结果为后续木工圆锯片钢材的改良提供了新的思路和方法,有望推动木质加工工具行业的进一步发展。

Effects of temperature and Nickel content on magnetic properties of Ni-doped ZnO

Magnetic properties of diluted magnetic semiconductors (DMSs), Ni-doped ZnO materials, prepared by sol-gel method were investigated by measuring magnetization as functions of magnetic field. The Ni content affects the magnetic properties at low sintered temperature but it has few effects on the magnetic properties at high sintered temperature. The sintered temperature has great effects on the magnetic properties of Ni/ZnO at high original mole ratio of Ni/Zn while it has slight effects on the magnetic properties of Ni/ZnO at low original mole ratio of Ni/Zn whatever low or high sintered temperature.

In-situ observation of microstructural evolution in reheated low carbon bainite weld metals with various Ni contents

Microstructural evolution in weld metals was in-situ observed through utilizing a laser scanning confocal microscope at two cooling rates.The specimens with various nickel contents were adopted for the observation.In the specimen with low fraction of Ni（≤2 wt.%）,granular bainite microstructure（i.e.broad surface relief）transformation from intragranular nucleation site was in-situ observed,while,lath bainite microstructure originating from grain boundary of austenite was in-situ observed for specimens with high mass percentage of Ni（≥4 wt.%）.With increasing nickel content,the transformation temperature dropped.The prior austenite grain size was initially depressed and subsequently coarsened dramatically with the addition of Ni.The microstructure difference was ascribed to various nucleation sites and growth direction in the matrix.On account of those observations,not only the chemical component,cooling rate and microstructure were systematically correlated,but also the microstructural evolution was definite.

Selective laser melted high Ni content TiNi alloy with superior superelasticity and hardwearing

TiNi alloys with high content Ni(52-55 at.%)are perfectly suitable for preparing wear-and corrosionresistant parts that service on the space station,spacecraft,and submarine,because of their superior superelasticity,high strength,and hardwearing.However,the fabrication of complicated Ni-rich TiNi parts by the traditional machining method often faces problems of poor precision,low efficiency,and high cost.In this work,we succeed in preparing an excellent Ti_(47)Ni_(53) alloy by selective laser melting(SLM),and thus,open a new way for the efficient and precise formation of complicated Ni-rich TiNi parts with superelasticity and hardwearing.An optimized processing window for compact parts without defects is reported.The elaborately fabricated Ti_(47)Ni_(53) alloy exhibited a breaking strain of 11%,a breaking stress of 2.0 GPa,a superelastic strain of 9%,and a better hardwearing than that of casting and quenched Ti_(47)Ni_(53) alloy.Besides,the microstructure,phase transformation,and deformation,as well as their influence mechanisms are investigated by in situ transmission electron microscope(TEM)and high-energy X-ray diffraction(HE-XRD).The results obtained are of significance for both fundamental research and technological applications of SLM-fabricated high Ni content TiNi alloys.

Effects of Ni content and tempering temperatures on microstructure and properties of medium-carbon cast steel

The microstructure evolution and properties of medium-carbon cast steel alloyed with different Ni contents after tempering at various temperatures have been investigated.The addition of 0.47-1.59 wt.%Ni content results in the formation of 16%-36% retained austenite(RA).The blocky and irregular-polygonal RA mainly forms along the prior austenite grain boundaries,and the tempering temperature does not affect the RA content.The hardness of medium-carbon cast steel is affected by the precipitation of carbides and the hardness of martensite.Excessive RA content is the main cause of intergranular impact rupture and low impact energy.The long-strip carbides formed after tempering at 320℃ would further reduce the impact energy of medium-carbon cast steel.When tempering at 220 and 380℃,the increase in impact energy is attributed to the formation of rod-like and spherical carbides and the low-carbon martensite.For the medium-carbon cast steel with high impact energy,its impact-abrasive wear resistance is more excellent.Micro-cutting and delamination are the primary wear mechanisms.

Effect of cyclic heat treatment on abnormal grain growth in Fe-Mn-Al-based shape memory alloys with different Ni contents

Cyclic heat treatment that can continuously promote abnormal grain growth is widely used for the prepa-ration of single-crystal Fe-Mn-Al-based shape memory alloys.However,it takes a long time to prepare large-size Fe-Mn-Al-based alloy single crystals via the reported cyclic heat treatments.Meanwhile,the long-time cyclic heat treatment at high temperatures leads to the development of defects including oxidation and a decrease in Mn,which would deteriorate superelasticity in the Fe-Mn-Al-based shape memory alloys.To shorten the fabrication time of single crystals,the effect of the cyclic heat treatment process on the abnormal grain growth in the Fe-Mn-Al-based alloys with different Ni contents was systematically investigated.It is found that the abnormal grain growth of Fe-Mn-Al-based alloys was not significantly affected by the Ni contents(within 2.1 at.%-6.2 at.%).In addition,the abnormal grain growth could be promoted by 1-2℃ min^(-1) cooling rate,high solution temperature,and multiple cycles,while it was insensitive to other processes including heating rate,dual-phase time as well as long-time solution treat-ment.These findings can guide optimizing the fabrication process of single crystals by cyclic heat treat-ment.Finally,the Fe_(41.9)Mn_(37.8)Al_(14.1) Ni_(6.2) single crystal prepared by the optimized cyclic heat treatment showed a recoverable strain of about 4%.

Fe、Ni元素微合金化对Al-11Si铝合金微观组织及力学性能的影响

本研究利用扫描电子显微镜(SEM)、能量散射X射线光谱(EDS)和拉伸试验机,研究了Ni(1.2及1.6wt.%)和Fe(0.6及0.8wt.%)含量对Al-11Si铝合金的微观组织及不同温度下的力学性能的影响。实验结果表明,适量的Ni元素对于Al-11Si合金中富含Fe相的类型、形态和分布具有积极作用。在Al-11Si铝合金中添加1.2wt.%Ni和0.6wt.%Fe可以生成一种类似“汉字状”的富Fe强化相。当进一步增加到1.6wt.%Ni和0.8wt.%Fe后,富Fe相变为了长针状,对Al基体产生严重的割裂作用,降低了合金力学性能。由于含有1.2wt.%Ni和0.6wt.%Fe的Al-11Si铝合金中生成了“汉字状”富Fe强化相,合金的高温拉伸性能得到了显著改善。在350℃的测试温度下,Al-11Si铝合金的抗拉强度(UTS)达到了139 MPa。

含Ni量、渗氮层深度及喷丸强化对42CrMo齿轮弯曲疲劳性能影响研究

针对不同含Ni量、渗氮层深度和喷丸强化组合的42CrMo齿轮开展弯曲疲劳试验,探究了不同工艺组合的齿轮弯曲疲劳极限提升效果,为齿轮抗疲劳制造提供工艺指导。基于随机森林算法分析了不同工艺组合齿轮的表面硬度、渗氮层深度、表面残余应力和含Ni量对弯曲疲劳极限的贡献度,采用多元回归建立了考虑表面硬度、渗氮层深度、表面残余应力和含Ni量的齿轮弯曲疲劳极限预测公式。预测值与试验值相比,最大误差可以控制在7.80%以内,为工程应用中快速、低成本评估齿轮弯曲疲劳极限提供了理论依据。

Ni含量对CrN涂层抗磨蚀性能的影响研究

目的探究在模拟海洋环境下,Ni的掺入对CrN涂层耐磨性能的影响,研究不同Ni含量的CrNiN涂层的磨蚀行为。方法采用磁控溅射方法对CrNiN涂层中的Ni含量进行调控,制备CrN涂层、Ni掺杂含量分别为15.85%(原子数分数)和39.06%的CrNiN涂层。通过干摩擦试验和模拟海水磨蚀试验,对3种涂层的力学性能和磨蚀行为进行研究对比,并分析其摩擦损伤机理。结果在干摩擦试验条件下,CrNiN涂层的摩擦学性能主要由涂层的力学性能决定,Ni原子数分数为15.85%的CrNiN涂层兼具高硬度和良好韧性,磨痕最浅,其磨损率在3种涂层中最低,为9.1×10^(-7)mm^(3)/(N·m),而在模拟海洋磨蚀的开路电位(OCP)下,Ni原子数分数为15.85%的CrNiN涂层的磨损率大于CrN涂层,CrN涂层具有最低的摩擦因数以及最低的磨损率。3种涂层在正电位(+0.6 V)时的磨损率显著大于开路电位(OCP)下的磨损率,说明腐蚀降低了涂层的耐磨性。通过对腐蚀产物进行分析,表明CrN的腐蚀产物主要是CrO_(2)以及Cr_(2)O_(3),具有一定的润滑作用,而含Ni的CrNiN涂层在腐蚀过程中产生了NiO,对涂层的耐磨性产生了不利影响。结论在干摩擦试验条件下,CrNiN涂层的摩擦学性能主要由涂层的力学性能决定,Ni原子数分数为15.85%的CrNiN涂层兼具高硬度和良好韧性,从而更耐磨。在模拟海洋磨蚀试验条件下,CrNiN涂层的腐蚀产物严重影响其磨蚀性能。

Effects of Ni Content and Ball Milling Time on the Hydrogen Storage Thermodynamics and Kinetics Performances of La–Mg–Ni Ternary Alloys

The eifects of Ni content and ball milling time on the hydrogen storage thermodynamics and kinetics performances of asmilled La5Mg95-xNix(x=5,10,15)ternary alloys have been investigated.The evolution of microstructure and phase of experimental alloys in the absorption/desorption process has been characterized by XRD,SEM and HRTEM.The hydrogen storage kinetics and thermodynamics performances and PCI curves have been tested using the Sievert apparatus.It is found that the rising of Ni content remarkably improves the hydrogen storage kinetic performance,but reduces hydrogen storage capacity.And with the increase in milling time,hydrogen desorption activation(Ea)value decreases firstly and then increases;the minimum value is 47.6 kJ/mol,and the corresponding milling time is 10 h for La5Mg85Ni10 alloy.As for the thermodynamics properties,the hydrogenation enthalpy(△H)and hydrogenation entropy(△S)both decrease firstly and then increase with the rising of Ni content and milling time.The composite La5Mg85Ni10 alloy milled for 10 h exhibits the best thermodynamics and kinetics performances,the lowest Ea of 47.6 kJ/mol,absorption of 5.4 wt.%within 5 min and desorption of 5.2 wt.%within 3 min at 360℃and the lowest△H and△S of 72.1 kJ/mol and 123.2 J/mol/K.

Effect of sodium content on the interaction between Ni and support and catalytic performance for syngas methanation over Ni/Zr–Yb–O catalysts

In this paper, Ni/Zr–Yb–O catalysts with different sodium contents are prepared by a co-precipitation method, using aqueous Na2CO3 solution as a precipitant, and the effect of sodium on the catalyst structure and catalytic performance for syngas methanation is extensively investigated using five Ni/Zr–Yb–O catalysts, containing 0, 0.5, 1.5,4.5 and 13.5 wt% Na^+, those are denoted as Cat-1, Cat-2, Cat-3, Cat-4 and Cat-5 respectively. It is found that the interaction between Ni and support determines the catalytic performance of Ni/Zr–Yb–O and the residual sodium content negatively affects the interaction between Ni and support. Cat-1 exhibits an excellent catalytic performance.During a long run time of 380 h, no deactivation is observed and both CO conversion and CH4 selectivity maintain a level above 90%. However, Cat-3 and Cat-5 suffer rapid deactivation under the same reaction condition. The characterization results indicate the strong interaction between Ni and support enables Cat-1 to possess well dispersed Ni species, resistance to sintering and carbon deposition and thus the excellent catalytic performance. However, the presence of sodium ions over Ni/Zr–Yb–O degrades the interaction between Ni and support and the catalytic performance, especially for the stability. The relative weak interaction between Ni and support results in severe sintering of both ZrO2 and Ni under the reaction condition, carbon deposition and the poor catalytic performance.

硅、镍含量与制备工艺对Al-Si-Ni合金组织和热学性能的影响

利用普通凝固、水冷铜模亚快速凝固和水冷铜模亚快速凝固复合热处理(520℃×6 h)3种工艺,分别制备了Al-11Si-5Ni合金、Al-22Si-10Ni合金和Al-33Si-15Ni合金,研究了不同合金的显微组织和热学性能。结果表明:Al-11Si-5Ni共晶合金在凝固过程中仅发生Al-Si-Al_(3)Ni三元共晶反应,形成由α-Al相、共晶硅相和共晶Al_(3)N相组成的三元共晶组织;Al-22Si-10Ni合金与Al-33Si-15Ni合金为过共晶合金,组织由初生硅相、初生Al_(3)N相和三元共晶组织组成,其凝固过程分为初生硅相析出、初生硅相与Al_(3)Ni相的共同析出以及Al-Si-Al_(3)Ni三元共晶反应3个阶段;随着镍、硅含量的同步增加,初生硅相与Al_(3)Ni相粗化;与普通凝固工艺相比,水冷铜模亚快速凝固工艺可以细化合金组织,而热处理使共晶硅相与共晶Al_(3)Ni相发生球化。随着硅、镍含量的同步增加,合金的热导率与热膨胀系数均下降,而水冷铜模亚快速凝固复合热处理可以有效提升合金的热导率。水冷铜模亚快速凝固复合热处理工艺制备的Al-22Si-10Ni合金具有优异的综合性能,其室温热导率为129.9 W·m^(-1)·K^(-1),100℃热膨胀系数为13.8×10^(-6) K^(-1),25~100℃平均热膨胀系数为12.9×10^(-6) K^(-1)。

Effect of cobalt content on electrochemical performance of La-Mg-Ni system (Ce_2Ni_7-type) electrode alloys

In order to improve the cyclic stability of La-Mg-Ni system （Ce2Ni7-type） alloy electrode, small amount of Co was added in La0.75Mg0.25Ni3.5 alloy. The effect of Co on electrochemical performance and microstructure of the alloys were investigated in detail. XRD results showed that the alloys had multiphase structure composed of （La, Mg）2Ni7, LaNi5 and small amount of LaNi2 phases. The discharge capacity of the alloys first increased and then decreased with increasing Co content. At a discharge current density of 900 mA/g, the HRD of the alloy electrodes increased from 81.3% （x=0） to 89.2 % （x=0.2）, and then reduced to 87.8 % （x=0.6）. After 60 charge/discharge cycles, the capacity retention rate of the alloys enhanced from 52.67% to 61.32%, and the capacity decay rate of the alloys decreased from 2.60 to 2.05 mAh/g per cycle with increasing Co content. The obtained results by XPS and XRD showed that the fundamental reasons for the capacity decay of the La-Mg-Ni system （Ce2Ni7-type） alloy electrodes were corrosion and oxidation as well as passivation of Mg and Lain alkaline solution.

奥氏体不锈钢全奥氏体组织熔敷金属中Ni含量对力学性能影响

为了研究Ni含量对全奥氏体组织熔敷金属力学性能的影响,采用铬当量相近、Ni质量分数不同的6种E316LMn-15焊条,通过控制其它化学成分,避免金属间化合物的形成并减弱了热裂倾向。分别对SMAW施焊后熔敷金属进行光学金相组织观察、铁素体测量、室温拉伸试验和-196℃冲击试验。结果表明,熔敷金属均为以奥氏体模式凝固的全奥氏体组织,具有良好的室温拉伸性能,抗拉强度均在520 MPa以上,屈服强度均超过380 MPa,断后伸长率也都在35%以上;同时熔敷金属均具有较高的低温韧性,-196℃平均冲击吸收能量均超过60 J。Ni的质量分数在15.58%~16.04%范围内,-196℃平均冲击吸收能量提升幅度大于Ni质量分数在16.04%以上的熔敷金属,且Ni质量分数在16.27%以上的熔敷金属低温冲击吸收能量趋于稳定,Ni质量分数为16.85%的试样-196℃平均冲击吸收能量高达90.4 J。

金川Ⅰ号岩体橄榄石Ni-MgO相互关系及其地质意义

金川超镁铁质岩体赋存着仅次于加拿大Sudbury和俄罗斯Noril'sk-Talnakh的世界第三大在采铜镍硫化物矿床,岩体以一系列的NE向断层为界分成四个小岩体,由西至东依次为:Ⅲ、Ⅰ、Ⅱ、Ⅳ岩体。Ⅰ号岩体主要由二辉橄榄岩、含辉橄榄岩和橄榄二辉岩构成,橄榄石在各岩相中均为保存较好的主要造岩矿物。本文研究得到金川Ⅰ号岩体上部二辉橄榄岩和含辉橄榄岩中橄榄石的镁橄榄石Fo值介于83.9～85.7,而其Ni含量为1396×10^(-6)～2043×10^(-6),大多低于从S不饱和玄武岩浆中结晶出采的橄榄石的Ni含量。模拟计算结果表明橄榄石较低的Ni含量是因为橄榄石结晶的同时,发生了强烈的硫化物熔离;橄榄石的Fo-Ni关系还因与晶间硅酸盐熔浆的物质交换而发生改变。模拟计算还证明大约有30%的晶间硅酸盐岩浆与橄榄石发生Fe-Mg物质交换反应,导致早结晶橄榄石的Fo值减少了1～1.5。同时,橄榄石较小的Fo值变化表明,在橄榄石结晶和硫化物熔离过程中,不断有新的岩浆贯入和补充。

Ni含量对SHS法合成TiC-Ni基金属陶瓷的影响

利用ＳＨＳ结合准热等静压（ＰＨＩＰ）技术制备了ＴｉＣ－Ｎｉ基金属陶瓷，理论分析和实验显示，绝热温度Ｔａｄ和燃烧温度Ｔｃ 随Ｎｉ含量的增加而降低，反应温度影响产物的组织形貌，Ｎｉ含量的增加使合成的ＴｉＣ颗粒尺寸变小，并且逐渐趋向于规则的球形。最后的产物均由ＴｉＣ和Ｎｉ两相组成。产物的致密度随Ｎｉ含量的增加逐渐提高，硬度值随Ｎｉ含量的变化而变化，两种因素的作用使硬度值在Ｎｉ含量为２０％ 时达到最大。