工艺参数对球磨法制备Mg-Cu系非晶态合金的影响

研究了工艺参数对球磨法制备Mg Cu系非晶态合金的影响,讨论了合金成分、球磨参数、过程控制剂等因素对非晶形成过程的影响。XRD测试结果表明:工艺参数决定球磨法最终产物的热力学状态和结构。     

机械合金化诱导难互溶系Cu-Cr合金固溶度扩展的研究

采用机械合金化工艺制备Cu-4%Cr和Cu-7%Cr(原子分数)二元合金粉末,利用XRD,SEM和TEM研究机械合金化过程中粉末的微观形貌和显微组织结构,测量了不同球磨时间粉末的氧含量以及显微硬度.结果表明:在一定的球磨时间内,Cu-Cr合金粉末随着高能球磨的进行,晶粒逐渐细化至纳米尺寸,晶格畸变增加,但进一步球磨会导致铜的晶格常数有所增加,畸变降低.实验证明,在固态下几乎不互溶的Cu-Cr合金,经球磨40 h的机械合金化,Cr在Cu中的固溶度明显提高.     

制备工艺对无钴AB5型贮氢合金的相结构和电化学性能的影响

用真空熔炼、快淬工艺以及球磨工艺制备稀土基无钴AB5型La（NiMnAlFe）5贮氢合金，用XRD测试了合金的相结构，并测试了不同制备工艺下合金的电化学性能。研究了制备工艺对无钴合金的相结构和电化学性能的影响。结果表明，由真空熔炼和快淬工艺制备的合金为CaCu5型单相结构，球磨合金由CaCu5型相和游离Ni相组成，并出现了非晶化趋势。快淬和球磨均使合金的放电容量降低，循环稳定性提高，但球磨工艺的影响更为显著，主要原因是球磨后合金中出现非晶化趋势。     

高能球磨过程Fe－Ni机械合金化特点

研究了Ｆｅ、Ｎｉ粉末在氢气保护下的机械合金化过程。利用ＸＲＤ和ＳＥＭ研究了球磨过程粉体的显微组织结构，测量了不同球磨时间粉体的显微硬度。结果表明，经３ｈ球磨便实现了Ｆｅ－Ｎｉ的完全合金化，合金的组织结构为纳米晶超饱和α固溶体（ｂｃｃ）和γ固溶体（ｆｃｃ）两相混合组织。继续球磨，过饱和α相逐渐分解并向γ相转化。根据衍射图分析了球磨过程的微观应变和晶粒尺寸及其对粉末显微硬度的影响。     

高能球磨对新型TiC钢结硬质合金组织和性能影响的研究

采用行星式球磨机对Fe-3.0Cr-3.0Mo-0.5Cu-0.5C-33TiC新型钢结硬质合金混合粉末进行高能球磨,对不同球磨时间粉末的形貌和粒度进行观察,测定了烧结后合金的密度、硬度和抗弯强度,并对其组织结构进行了分析.结果表明：球磨初期,粉末粒度迅速减小,粉末出现片状形貌,随着球磨时间增加,粉末粒度减小速度变缓,最后趋于稳定,片状形貌逐渐消失,不规则球形形貌增多.球磨过程中,Fe与其它添加元素（C、Mo、Cu）发生合金化反应.在一定时间内,随着球磨时间的增加,混合粉末成分均匀性增加,合金的密度、硬度和抗弯强度也明显提高.     

用MA方法研究添加Si,Fe元素对77Fe21B2Si合金结构的影响

利用高能球磨机研究了添加Ｓｉ、Ｆｅ元素对７７Ｆｅ２１Ｂ２Ｓｉ合金在球磨过程中的结构变化，作者用结构组态曲线非常明显的反映了随球磨时间增加各组态的变化。实验证明Ｓｉ元素很容易在其它元素合金化，同时Ｓｉ又在固态反应非晶经中起着重要作用，而Ｆｅ只是提供基础结构。     

多孔Ni-Al系金属间化合物制备技术研究进展

Ni-Al系金属间化合物具有低密度、良好的导热性、优良的高温力学性能以及抗高温氧化性能等特性引起了研究人员的广泛关注,期待作为高温结构材料替代传统不锈钢和镍基高温合金。多孔Ni-Al金属间化合物由于具有孔隙结构,赋予了传统Ni-Al系化合物更多的功能特性以及轻量化特点,利用其孔隙特性可用做高温氧化环境以及酸碱腐蚀条件下的过滤材料或催化剂材料。基于原料形式与制备工艺的差异,本文将多孔Ni-Al系金属间化合物的制备方法分为3大类:粉末冶金法(反应合成法、燃烧合成法)、化学脱合金法和定向凝固法,分析了各制备技术的特点及其孔隙构筑方式,展望了未来的发展趋势,期望将多种制备技术相结合拓展其应用领域并满足工程化需求。     

非晶纳米晶双相结构Sn-Co-C负极材料的制备及性能表征

采用真空气雾化与高能机械球磨法结合,制备SnCoC复合材料作为锂离子电池负极材料,操作简单,时间短,易于实现工业化.采用X射线衍射(XRD)和扫描电子显微镜(SEM)检测合金粉末及复合材料的相结构和表面形貌,结果发现碳的引入不会对合金相结构产生影响,它以无定形碳形式存在,随着球磨时间的增加,合金由晶态向非晶态转变,且颗粒变得均匀,部分颗粒尺寸甚至达到纳米级.将制得材料组装成模拟电池,测试其电化学特性,结果表明:球磨20h的Sn-Co合金比未球磨的合金负极的比容量高且循环更稳定,而将台金与石墨球磨后,所得复合材料的电化学性能进一步提高,首次库仑效率最高达90.6％,50次循环后容量保持率66.7％.分析可知:通过将锡钴合金弥散在无定形碳中,获得非晶纳米晶双相结构的SnCoC复合材料.非晶材料的各向同性,能够缓冲Li-Sn在合金化-去合金化过程中产生的结构和电场应力;纳米级尺寸的材料内部空隙多,有利于锂离子的扩散;碳材料除了稳定的结构外还可以提供一定的容量.这些有利因素结合起来,极大改善了材料的电化学性能.     

球磨AB_5型储氢合金对BH_4~-的催化性能与其电化学性能的相关性研究

采用电弧熔炼和高能球磨方法联合制备了一系列不同球磨时间下的AB_5型MmNi_(3.55)Co_(0.75)Mn_(0.4)Al_(0.3)储氢合金样品,并对该系列合金样品的结构、电化学性能以及作为DBFC(直接硼氢化物燃料电池)阳极催化剂的催化性能进行了研究。探讨了合金样品的电化学性能与合金样品作为DBFC阳极催化剂对BH~-_4的催化性能之间的关系。研究结果表明,球磨没有改变合金的相组成,但改变了合金的相结构。所有球磨态AB_5型合金均由单一的CaCu_5型LaNi_5相组成。随着球磨时间的延长,合金非晶化程度越来越严重。随着球磨时间的延长,AB_5型合金样品的最大放电容量、放电性能以及循环稳定性均逐渐变差,同时球磨AB_5型合金作为DBFC阳极催化剂的催化性能以及稳定性也在逐渐变差。可见,球磨AB_5型合金的电化学性能与其作为DBFC阳极催化剂的催化性能呈正相关关系。铸态AB_5型MmNi_(3.55)Co_(0.75)Mn_(0.4)Al_(0.3)储氢合金样品呈现了最佳的综合电化学性能和作为DBFC阳极催化剂的催化性能。     

W-4.9Ni-2.1Fe 高比重合金的摩擦磨损行为

采用高能球磨和放电等离子体烧结技术制备W-4.9Ni-2.1Fe高比重合金,研究不同球磨时间对合金显微组织结构和摩擦磨损行为的影响. 结果表明:当球磨时间较短（2 h）时,合金粉末中Ni、Fe元素仍以单质的形式存在;随着球磨时间的延长,Ni(Fe)溶入W晶格中形成W的过饱和固溶体,W衍射峰强度逐渐变弱,峰形明显宽化,合金试样的相对密度呈下降趋势;适量的球磨时间（24 h）,既可以保证合金中黏结相的含量和均匀分布,又不至于引入过量的杂质元素而引起合金成分改变,合金拥有最优的耐摩擦磨损性能.      

Thermoelastic martensite and shape memory effect in B2 Base Ni-Al-Fe alloy with enhanced ductility

A ductile shape memory alloy of the Ni-AI-Fe system has been developed using principles through the control of microstructure. Addition of Fe to the binary Ni-Al shape memory alloy allows the introduction of a ductile face-centered cubic (fcc) phase in an otherwise extremely brittle β phase alloy, leading to an improvement in its ductility while retaining its ability to exhibit shape memory arising from the martensitic transformation of theβ phase to Ll₀ structure. It is shown that the transformation temperature in the ternary Ni-AI-Fe alloy can be easily controlled by the preannealing in the β+ γ region. Experimental results on the effect of different annealing treatments on the microstructures and the shape memory behavior in this alloy are presented and discussed.     

Design of the Precipitation Process for Ni-Al Alloys with Optimal Mechanical Properties: A Phase-Field Study

An attempt to design the heat treatment schedule for binary Ni-Al alloys with optimal mechanical properties was made in the present work. A series of quantitative three-dimensional (3-D) phase-field simulations of microstructure evolution in Ni-Al alloys during the precipitation process were first performed using MICRESS (MICRostructure Evolution Simulation Software) package developed in the formalism of the multi-phase field model. The coupling to CALPHAD (CALculation of PHAse Diagram) thermodynamic and atomic mobility databases was realized via TQ interface. Moreover, the temperature-dependent lattice misfits and elastic constants were utilized for simulation. The effect of the alloy composition and aging temperature on microstructure evolution was extensively studied with the aid of statistical analysis. After that, an evaluation function was proposed for evaluating the optimal heat treatment schedule by choosing the phase fraction, grain size, and shape factor of γ′ precipitate as the evaluation indicators. Based on 50 groups of phase-field-simulated and experimental microstructure information, as well as the proposed evaluation function, the optimal alloy composition, aging temperature, and aging time for binary Ni-Al alloy with optimal mechanical properties were finally chosen. The successful application in the present Ni-Al alloys indicates that it is possible to design the optimal alloy composition and heat treatment for other binary and even multicomponent alloys with optimal mechanical properties based on the evaluation function and the sufficient microstructure information. Additionally, the combination of the present method and the key experiments can definitely accelerate the material design and improve the efficiency and accuracy.     

Extended solid solution and nonequilibrium phase diagram for Ni-Al alloy formed during laser cladding

Due to rapid solidification in laser cladding, the composition of the solute in the cladding alloy often exceeds the solid solubility limit far beyond that expected from the equilibrium phase diagram. Also, the effects of various process parameters on the composition of the cladding alloy depend on the sign of the slope of the equilibrium phase diagram at the nominal composition of the cladding powder. This paper uses a mathermatical model to determine the composition of metastable alloys and to study the effects of various process parameters on the composition of extended solid solution in the cladding alloys of Ni-Al for which the slope of the equilibrium phase diagram is positive at the nominal composition of the Ni-Al cladding powder. The model considers concentration dependent freezing point and nonequilibrium partitioning of solute at the solid-liquid interface. Because of this, nonequilibrium phase diagram can be obtained by following the methodology of this paper.     

耐热合金Cr25Ni30组织性能研究

研究设计了三种不同成分Cr25Ni30耐热合金,并对其组织特征及常温和高温性能进行了测定。结果表明:w(Al)为5%的合金室温拉伸强度最高,金属组织中出现较多的Ni-Al金属间化合物,显著降低其塑性;w(Al)为3%的合金塑性最好,但强度较低;w(Nb)为2%的合金抗氧化性最好,高温强度最高,综合性能最好。     

Transmission electron microscopy study of martensites in laser-clad ni-ai bronze on aluminum alloy AA333

The microstructure and crystal structure of laser-clad Ni-Al bronze on Al alloy AA333 were investigated with scanning electron microscopy (SEM) and transmission electron microscopy (TEM) combined with energy-dispersive X-ray spectroscopy (EDX). The SEM and TEM revealed two kinds of martensites in the clad region: sheet martensite and lath martensite. Selected area diffraction (SAD) analysis showed that the sheet martensite had a close-packed structure with different stacking modulations. Two crystal structure analysis procedures based on a hexagonal unit cell were applied to identify the stacking periods and orders of the sheet martensite. The analysis showed that a nine-layer stacking mode specified as ABCBCACAB was predominant and that an 1 1-layer stacking mode specified as ABCBCACABAB was also locally present. The crystal structure of the lath martensite was identified as face-centered cubic (fcc) by SAD. No ordering of alloying elements was detected in the sheet and lath martensites.     

焦炭微晶结构特性研究

选取23个单种煤进行了焦炭性能的影响因素研究,在20 kg试验焦炉中进行炼焦试验,并进行焦炭质量分析试验.通过23个单种煤焦炭的X射线衍射图,计算焦炭微晶结构参数,研究焦炭微晶结构特性与焦炭宏观性能关系.结果表明:焦炭气孔壁最基本单元--微晶结构是影响焦炭宏观性能的最本质因素.焦炭微晶结构与炼焦煤的煤化度关系密切,致密度和单元大小在煤岩镜质组反射率Rr为1.2%左右达到最大值.     

Effect of aluminum additions on the microstructure of Ni-V superalloys

The effect of aluminum additions on the microstructure and the phase composition of an Ni-25 at % V alloy is studied. It is shown that the introduction of aluminum into Ni-V alloys decreases their maximum possible high-temperature strength, since an ordering-separation phase transition occurs in the Ni-Al diffusion couple at temperatures slightly higher than 1200°C with the formation of quasi-liquid aluminum atom clusters in the solid solution lattice.     

The time dependent behavior of the ostwald ripening for the finite volume fraction

On the basis of the theory of Tokuyama and Kawasaki on the Ostwald ripening, we investigate the time dependent behavior from the late stage into the scaling region. We calculate numerically the transient behavior of the droplet size distribution function and the average droplet radius for various initial conditions. Moreover we compare the obtained results with the experiments in which the transient behavior of the Al-Li, Ni-Al and Ni-Si alloy systems were investigated for various ageing temperatures. The present theoretical results are in good agreement with these experimental results.     

The influence of temperature gradients on ostwald ripening

Numerical simulations are used to study particle coarsening in the presence of a small linear temperature gradient in a system containing 10 and 20 pct volume fractions of coarsening phase. Temperature gradients are found to have an effect on both the microstructure and the kinetics of the system undergoing coarsening. The magnitude of the effect is dependent upon the thermophysical parameters of the alloy, the magnitude of the gradient, and the initial conditions of the system. Estimates for the magnitude of the effect are given for the Pb-Sn, the Ni-Al, and the W-Ni-Fe systems.     

Effect of methane on sulfur dioxide and sodium sulfate-lnduced corrosion of nickel-base alloys

The corrosion of nickel-base binary alloys, with up to 20 wt pct Cr or Al, by sulfur dioxide contained in a nitrogen gas stream, has been found to be considerably enhanced between 800 and 1000°C in the presence of low concentrations of gaseous methane. The magnitude of the effect, which is related to the ability of the alloy surface to catalyze the decomposition of the hydrocarbon to solid carbon, decreases with increasing Cr and Al content of the alloy. Ni-Al alloys containing less than 10 wt pct Al are more readily attacked by SO₂ alone than are the corresponding Ni-Cr alloys, although the deleterious effects of added methane are more marked in the Ni-Cr series. The extent of high temperature corrosion of these alloys by deposited sodium sulfate at 900 to 1000°C is also generally increased when small amounts of methane are introduced, although in this case the addition of Cr to the alloy confers greater corrosion resistance than does the addition of an equivalent concentration of Al. In the presence of either sodium sulfate or SO₂, the addition of methane to the ambient nitrogen atmosphere results in localized reducing conditions and increased sulfur potentials near the alloy surface.