放电等离子烧结W-Ni-Fe合金的显微组织与性能研究

采用高能球磨机制备了不同球磨时间的W-Ni-Fe高比重合金粉,采用XRD分析了粉末相的变化.应用放电等离子烧结技术制备了W-Ni-Fe合金.采用SEM和EDX对烧结合金的形貌、断口和成分进行了分析,并且用维氏硬度计测量了样品的硬度.结果表明,球磨20h的SPS W-Ni-Fe合金具有较好的显微组织,断裂方式表现为W晶粒的穿晶解理断裂和粘结相的穿晶延性断裂特征,并且具有较高的硬度.     

真空烧结中W-Ni-Fe系高比重合金的挥发与控制

钨基高比重合金因具有高密度和高强度等一系列优异的性能而得到了广泛的应用,尤其是在军事领域尤为重要,而且钨基高比重合金烧结的方式也多种多样,现代工业中应用最广泛的烧结方式就是氢气烧结和真空烧结,该文主要研究的是钨基高比重合金中W-Ni-Fe系高比重合金的真空烧结,主要研究方向是如何防止合金中Ni、Fe元素在真空烧结中挥发的具体工艺方法。     

稀土改性高密度W-Ni-Fe合金的研究现状及发展趋势

高密度W-Ni-Fe合金因其具备许多优异性能,作为一种重要的军民两用合金材料,广泛应用于国防军工、航空航天、先进制造业等众多领域。稀土元素作为工业的"维生素",因其独特的性质及活性,添加在合金中,能有效的抑制晶粒长大、细化晶粒组织和提高合金力学性能,已成为制备高强韧、超细晶钨合金的重要途径和研究热点。综述了国内外采用稀土元素及其氧化物强化细晶钨合金的研究进展,分析了目前存在的问题,并对未来进一步提高合金的性能提出了展望。     

纳米晶钨粉对液相烧结93W合金组织性能影响

采用高能机械球磨方法制备了超细钨粉,经冷等静压和1465℃分解氨气氛中液相烧结制得高密度钨合金.研究了纳米晶亚微米颗粒钨粉对烧结态93W-4.9Ni-2.1Fe高密度钨合金微观组织及性能的影响.研究表明:采用超细钨粉与低温液相烧结技术,获得了高相对密度(大于99.7%)的烧结态高密度钨合金,且细钨颗粒组织均匀分布于粘结相中;与采用亚微米颗粒钨粉的烧结态钨合金相比较,不仅微观组织弥散分布,而且具有较高的力学性能;液相烧结态钨合金的力学性能主要与原始钨粉粒度及烧结温度有关.     

几种钼合金的硬化机理和再结晶性能

研究了热加工处理对固溶强化的Mo-0.5Ti合金和颗粒强化的TZM合金显微组织的影响.2种合金均采用粉末冶金工艺制备,原料粉末为Mo,TiH2,ErH2和石墨.第1阶段分别按合金配比配料混合,冷等静压制以后在1 800℃以上温度烧结5 h.烧结后2种合金的成分列于表1.烧结材轧制成棒,接着分2阶段旋锻,总变形度为2.87(对数值).     

粉末混合方法和粉末粒度对钨重合金性能的影响

钨重合金因具有高密度、高塑性、高强度和高韧性,被广泛用于辐射防护等方面.钨重合金是由钨、镍、铁、铜粉末在真空和(或)氢气炉中液相烧结而成,在1500℃的液相烧结温度下,获得高密度合金.但是,高密度并不意味着其物理性能优异,物理性能对加工变化十分敏感.这些变化因素的研究包括烧结温度、烧结时间、烧结气氛、粉末性能和热处理温度,但却忽视了粉末混合方法和粉末粒度的影响.此项工作的目的就是研究粉末混合和粉末粒度对90W-7Ni-3Fe和92.5W-5.25Ni-2.25Fe重合金塑性和微观组织的影响.     

提高Ti-12Mo烧结合金的密度与强度

研究人员在尽可能低的温度下烧结制得高密度、高强度的Ti-Mo合金,并分析研究了其中添加少量C,Ni和Co对合金密度和强度的影响.     

一种W-Ni-Al-Fe系易碎钨合金材料的研究

研究了一种W-Ni-Fe-Al系易碎穿甲弹芯材料,该材料采用冷等静压成型和液相烧结工艺制备.经金相检验和拉伸断口扫描电镜分析,该材料在烧结过程中可形成Al2O3脆性壳体分布于黏结相中,起到降低抗拉强度、提高弹芯破碎性的作用.性能测试表明,该材料与相同钨含量的93W-Ni-Fe合金相比,动态压缩强度相当,而静拉伸强度下降了约200MPa,延伸率下降了约20%.     

后续烧结对爆炸压实CuCr合金性能的影响

采用机械合金化工艺由Cu,Cr元素粉按重量比各半合成CuCr预合金粉,尔后爆炸压实工艺制坯,再加后续烧结制备了电触点材料CuCr合金,着重研究了后续烧结对爆炸实CuCr合金性能的影响,结果表明,真空烧结略微提高爆炸压实的CuCr合金的密度,而氢气烧结处理反而使其密度降低,真空烧结和氢气烧结都能显著降低CuCr合金硬度,而且氢气烧结降低得更明显,真空烧结和氢气烧结都显著提高CuCr合金的电导率,而且真空烧结提高更显著。     

球磨时间对镍基ODS合金拉伸性能的影响

研究了球磨时间对Y2O3氧化物弥散强化(ODS)镍基高温合金机械合金化和拉伸性能的影响.镍基高温合金采用机械合金化和热压烧结方法制备.镍基ODS高温合金粉末是在行星式球磨机上进行球磨.采用扫描电镜及X射线衍射分析了球磨时间对镍基ODS合金粉末形貌和物相的影响.研究结果表明,Y2O3氧化物弥散强化镍基高温合金机械合金化粉末尺寸随研磨时间的增加先增大后减小,8h粉末颗粒尺寸达到最大,之后粉末颗粒尺寸逐渐减小,28h后,镍基ODS合金粉末尺寸稳定且均匀.拉伸结果表明,采用研磨28h的合金粉末制备的镍基ODS合金具有最高的抗拉强度(1300MPa).     

Superhard nanodisperse tungsten heavy alloys obtained using the methods of mechanical activation and spark plasma sintering

We have studied the structure and mechanical properties of nanodisperse tungsten-based heavy alloys of the W-Ni-Fe system. The temperature dependence of the density of compacted alloys exhibits a nonmonotonic character with a maximum that corresponds to the optimum temperature of sintering. The effect of the regime of solid-state pulsed spark plasma sintering (SPS) on the structure and mechanical properties of mechanically activated W-Ni-Fe heavy alloys has been studied. It is established that, using preliminary mechanical activation in a planetary ball mill and the subsequent high-rate SPS, it is possible to obtain superhard tungsten-based heavy alloys with mechanical properties that substantially exceed those of the analogous standard alloys.     

Coarsening of tungsten particles in W-Ni-Fe alloys

The coarsening kinetics of tungsten particles in W-Ni-Fe alloys during liquid phase sintering was studied. The particle growth rate increased with increasing volume fraction of tungsten, and the growth isotherms followed the cubic rate law, suggesting that the diffusion in liquid phase was the rate-limiting step. However, the particle size distributions were consistent with the reaction-controlled size distribution predicted by the theory of Liftshitz, Slyozov and Wagner. These experimental results could be explained by the diffusion-controlled growth according to the theory developed by Ardell.     

放电等离子烧结制备块体非晶合金研究进展

非晶合金又称“金属玻璃”,是由于超快速冷却凝固导致无法有序排列结晶,从而得到的一种长程无序结构。这种非晶合金与存在晶界和位错的普通合金相比,具有更加优异的力学及物化性能。由于粉末状或条状非晶合金在尺寸和性能等方面的限制,因而大尺寸、优异力学性能及软磁性能卓越的块体非晶合金的制备受到了大量关注与探究。放电等离子烧结技术以温度低、效率高、时间短及冷却速率快等优点,被认为是一种具有广阔发展前景的制备方法。对Fe基、Zr基、Al基及Ti基本身的特点,以及通过放电等离子烧结技术制备不同体系块体非晶合金的物理及化学性能的研究进行了较为全面的综述。概述了放电等离子烧结技术的原理及在制备块体非晶合金方面的优势;分析了放电等离子烧结技术和制备的块体非晶合金材料存在的问题,以及采用该技术制备块体非晶合金的发展前景。重点介绍了在采用该制备不同体系的块体非晶合金时,如何通过改变放电等离子烧结参数,或通过再加工、本身粉末添加元素等方法获得大尺寸、优异性能的块体非晶合金。     

放电等离子烧结(SPS)技术与新材料研究

放电等离子烧结(SPS)作为一种材料的绿色制备新技术,正成为国内外材料领域的研究热点.介绍了SPS的工艺特点和装置、国内外发展状况以及特殊的烧结机理;阐述了SPS在功能梯度材料、生物材料、超细或纳米晶WC-Co硬质材料、镁合金等新材料制备方面的应用及优势.最后分析了SPS技术亟待解决的问题和今后的发展趋势.     

Effecxt of Cu Addition on W—Ni—Fe Alloys Sintered at a Low Temperature

In this study,Cu was added as the third additive to lower the sintering temperature of W-Ni-Fe alloy .By adding 2wt pct Cu, 2 dense 93W-3.5Ni-1.5Fe-2.0Cu tungsten alloy was obtained by hot-pressing at a low temperature of 1573K which is a process of liquid-phase sintering.As a result,the morphology of W-Ni-Fe alloy changed obviously after the addition of Cu and the alloy had higher relative density and rupture strength.The mechanism of the densification of W-Ni-Fe-Cu alloy at the low temperature was then mainly investigated.It was found that ,part sintering activators Ni and Fe could exist in liquid form at 1573 K due to the addition of Cu, which made it easy for Ni and Fe to dissolve W and thus the full densification of W-Ni-Fe-Cu alloy at the low temperature was realized.     

Influence of minor elements additions on microstructure and properties of 93W-4·9Ni-2·1Fe alloys

Effects of elements rhenium and chromium additions on properties and microstructure of 93W-4·9Ni-2·1Fe alloys were investigated. Optical microscope (OM), scanning electron microscope (SEM) and EDAX energy spectrometer were used to characterize the microstructure and compositions of the alloys, respectively. The tensile strength and elongation of alloys were evaluated using the quasi-static tensile testing machine, and the relative densities of the alloys were evaluated using the Archimedes water immersion method. The experimental results indicated that when elements Re and Cr were in the range of 0–1·0 wt.%, relative density, elongation, tensile strength of 93W-4·9Ni-2·1Fe alloys varied from 99·4%, 26·4%, 997·2 MPa without Re additions to 99·5%, 8·6%, 1161·2 MPa with 1·0 wt.% Re addition, respectively. Rhenium generated solid-solution strengthening, grain refinement, reducing ductile tearing and increasing transcrystalline fracture, which resulted in the ductility reduction and the strength increase of the heavy alloys. With the increase of Cr content from 0–1·0 wt.%, the tensile strength, relative density and elongation of 93W-Ni-Fe alloy reduced from 997·2 MPa, 99·3%, 15% to 844·4 MPa, 95·2%, 5·7%, respectively. Element Cr formed interphases with elements W, Ni, Fe and O and gathered along the interface of the alloys, which induced interfacial cohesion and resulted in lower mechanical properties of 93W-Ni-Fe alloys.     

Effect of Cu Addition on W-Ni-Fe Alloys Sintered at a Low Temperature

In this study, Cu was added as the third additive to lower the sintering temperature of W-Ni-Fe alloy. By adding 2 wt pct Cu, a dense 93W-3.5Ni-l.5Fe-2.0Cu tungsten alloy was obtained by hot-pressing at a low temperature of 1573 K which is a process of liquid-phase sintering. As a result, the morphology of W-Ni-Fe alloy changed obviously after the addition of Cu and the alloy had-higher relative density and rupture strength. The mechanism of the densification of W-Ni-Fe-Cu alloy at the low temperature.was then mainly investigated. It was found that, part sintering activators Ni and Fe could exist in liquid form at 1573 K due to the addition of Cu, which made it easy for Ni and Fe to dissolve W and thus the full densification of W-Ni-Fe-Cu alloy at the low temperature was realized.     

MH/Ni电池复合贮氢合金负极材料的研究进展

制备复合合金是改善贮氢合金性能的一条有效途径.归纳了MH/Ni电池复合贮氢合金负极材料不同的制备方法.从机械合金化法、熔炼法、粉末烧结法和机械混合法等4个方面,对用于MH/Ni电池负极材料的复合贮氢合金的研究现状进行了分析和综述,并提出了目前研究中存在的几个问题.     

生物医用多孔钛及钛合金激光快速成形研究进展

多孔钛及钛合金具有良好的生物相容性和与人骨更匹配的力学性能,是人体理想的替代材料,因此其制备技术及相关性能研究引起了广泛关注。激光快速成形是一项先进的制造技术,在制备生物多孔金属材料时具有独特的优势。介绍了激光快速成形的工作原理和技术特征,根据成形工艺特点简要回顾了4种代表性激光快速成形技术(选择性激光烧结、选择性激光熔化、激光近净成形和激光立体成形)的国内外发展现状,并重点论述了这几种技术在制备生物医用多孔钛及钛合金方面的最新研究进展,最后指出了今后在该领域的主要研究工作。