高比重钨合金力学性能影响因素分析

首先考虑液相烧结工艺条件及组分对高比重钨合金微结构和各相性质的影响，再从细观力学的角度考虑高体积百分比钨合金微结构及各相性质对复合材料有效力学性质的影响，从而架起工艺条件及组分与钨合金力学性能之间关系的桥梁，为分析高比重钨合金性能从理论上建立一套方法，从材料设计和制备的角度实现对这种材料性能优化提供一种方案。并应用上述模型和方法对用粉末冶金法制备的两种不同钨含量的钨合金材料微结构和力学性能进行分析。     

钨管、钨喷嘴、钨坩埚等特殊钨金属和合金产

一、内容简介 钨合金作 为高温难熔材料在航空航天事业和军事方面的应用受到工业发达国家的高度重视。近年来特种钨金属和钨合金产品被广泛用于宇宙飞行器、反应堆的管路和穿甲弹中，由于它还具有极好的抗腐蚀性能，因而还可用作高温和腐蚀环境中使用的电触头。高比重钨合金在军事方面有着特殊用途外，如飞机、火箭、导弹、潜艇、鱼雷的导航陀螺仪，     

高比重钨合金沉淀强化的研究

综述了近年来高比重钨合金中沉淀强化的研究动态、采用的方法以及达到的水平，对沉淀强化的发展提出了建议。     

钨铼合金制备及应用

概述了粉末冶金法制备钨铼合金中的混料与还原工艺,以及未来可能用于制备纳米结构钨铼合金的新兴工艺。介绍了钨铼合金应用于热电偶和作为面向等离子体材料的研究现状,分析了钨铼热电偶在测温方面以及钨铼合金作为面向等离子体材料方面的发展趋势。     

粉末冶金难变形材料热静液挤压技术进展

综述了热静液挤压技术在烧结态粉末冶金难变形材料挤压成形与粉末体高致密化固结方面的研究进展。简述了热静液挤压工艺原理、工艺特点与适用范围,分析了热静液挤压润滑层形成的影响因素,介绍了热静液挤压润滑介质研制和热静液挤压技术在粉末冶金高比重钨合金、γ-TiAl基合金材料的挤压成形以及纳米晶铝合金、弥散强化铜合金、NdFeB永磁合金等金属粉末体材料的高致密化固结成形方面的应用,指出了热静液挤压工艺的技术优势与发展前景。     

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.     

电沉积钨及钨合金涂层的研究进展

金属钨及含钨涂层具有优良的性能,如高熔点、高硬度、良好的化学稳定性和较低的热膨胀系数,在多个领域被广泛应用,金属钨及含钨涂层有很多制备方法,其中电沉积法具有重要的地位。综述了熔盐电沉积钨涂层及溶液电沉积钨合金涂层的研究进展,并展望了熔盐电沉积钨涂层及溶液电沉积钨合金涂层的发展趋势。     

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.     

不同晶粒度钨合金动态力学性能研究

采用拉格朗日实验分析技术对1～3μm,10～15μm和30～40μm三种不同晶粒度细化钨合金材料91W-6.3Ni-2.7Fe在高应变率下的动态力学性能进行研究.得到三种不同晶粒度的钨合金在不同冲击速度下各拉氏位置的应力时程曲线.利用拉氏分析方法对钨合金在高应变率下的力学性质进行探讨,分析各拉氏位置的应变,比容,密度,应变率,比内能,质点速度等物理量的变化历史,讨论不同晶粒度尺寸对钨合金在高应变率下动态力学性能的影响,给出钨合金在应变率为104～105s-1时的应力应变曲线.     

新型电磁发射拦截弹对钨合金长杆弹拦截效果的数值模拟

本文提出了一种新型电磁发射拦截弹,以拦截弹与钨合金长杆弹碰撞过程为例,使用LS-DYNA程序建立了拦截弹和钨合金长杆弹的三维有限元模型。在拦截弹对钨合金长杆弹的拦截效果问题上进行了数值模拟分析,并得出了不同着角和钨合金长杆弹运动速度对拦截效果影响的关系曲线,给出了拦截弹与钨合金长杆弹碰撞后的速度变化及状态改变情况,结果表明,拦截弹对钨合金长杆弹起到了较好的拦截作用,两者碰撞后,钨合金长杆弹对装甲车辆的穿甲效果明显降低。     

钨基高比重合金的制备研究进展综述

综述了当前国内外钨基高比重合金制备的研究进展,介绍了WHAs制备工艺中存在的问题和当前的研究方向.采用机械合金化制取纳米预合金粉是WHAs制备取得突破性进展的新工艺之一;活化烧结和二步烧结可显著改善其力学性能;纳米粉末烧结技术的关键就是在得到全致密合金的同时,保持材料的纳米结构才能对性能作出很大的贡献.     

Electrokinetic treatment of firing ranges containing tungsten-contaminated soils

Tungsten-based alloys and composites are being used and new formulations are being considered for use in the manufacturing of different types of ammunition. The use of tungsten heavy alloys (WHA) in new munitions systems and tungsten composites in small caliber ammunition could potentially release substantial amounts of this element into the environment. Although tungsten is widely used in industrial and military applications, tungsten's potential environmental and health impacts have not been thoroughly addressed. This necessitates the research and development of remedial technologies to contain and/or remove tungsten from soils that may serve as a source for water contamination. The current work investigates the feasibility of using electrokinetics for the remediation of tungsten-contaminated soils in the presence of other heavy metals of concern such as Cu and Pb with aim to removing W from the soil while stabilizing in situ, Pb and Cu.     

Electronic mechanism of sintering: Some case studies on real systems

The paper reviews the role of electronic configuration model of condensed state in explaining the sintering behaviour of various alloys. The systems are copper base alloys, ferrous alloys containing phosphorus, tungsten based heavy alloys, Al-refractory carbide composites, 6061 Al-alloy composites, high speed steel composites and tungsten carbide based cemented carbides. These studies cover the research activities of the Powder Metallurgy Laboratory at IIT, Kanpur.     

Prospects of producing hard alloys based on submicron and nanoscale W and WC powders prepared by a chemical metallurgy process and with the use of self-propagating high-temperature synthesis

We present a brief review of research and design work aimed at producing tungsten-containing hard alloys for various applications. We examine the feasibility and prospects of using a chemical metallurgy method and self-propagating high-temperature synthesis (SHS) for the preparation of submicron and nanoscale hard-alloy powders as a key component of highly efficient state-of-the-art materials and products. Particular examples are presented of the use of submicron and nanoscale powders for the preparation of TVS tungsten-based heavy metallic alloys and VK tungsten carbide hard alloys for various applications. Their application fields are discussed and their properties are compared to those of their analogs produced by conventional powder metallurgy methods. Using the SHS of tungsten carbide as an example, we demonstrate a particular path from research to commercialization (from the discovery of SHS processes to commercialscale production) of key modern engineering materials: tungsten-based heavy alloys and tungsten carbidebased hard alloys.     

形变强化对93W-4.9Ni-2.1Fe合金组织及性能的影响

为研究形变强化工艺对93W-4.9Ni-2.1Fe性能的影响,采用大变形量旋转锻造工艺制备了93W-4.9Ni-2.1Fe合金,并利用SEM与TEM技术分析了旋转锻造态93W-4.9Ni-2.1Fe合金显微组织的形态与尺寸.结果表明:钨合金材料经形变强化后,钨晶粒内部出现由高密度位错形成的胞状组织以及长条状形变晶粒,且粘结相内位错密度较高;旋锻态93W-4.9Ni-2.1Fe合金在具有高强度的同时,保持着一定的延性;旋锻态钨合金的力学性能与变形量及粘结相的分布有关.     

Influence of hot extrusion on microstructure and mechanical properties of tungsten based heavy alloy

Microstructural characterisation and room temperature tensile testing were performed on a series of tungsten heavy alloys extruded at various temperatures. Ultimate tensile strength of the alloys increased with increasing extrusion ratio and with decreasing extrusion temperature down to 600°C. Fracture surface observations indicated that the tensile strength correlated with the tungsten cleavage failure mode. The matrix could inhibit the propagation of cracks initiated in the tungsten particles.

MST/3384     

Sigma Phase in Tungsten-Rhenium Alloys. I

In developing tungsten alloys for service both above the recrystallization temperature and below room temperature the main task is to make an alloy, which in addition to having a low ductile to brittle transition temperature in the recrystallized condition can readily be manufactured into various configurations.

Tungsten-rhenium alloys have been found to be useful for such applications, since they have a combination of high strength and good ductility. The best ductility is reached in alloys with a rhenium content close to the solubility limit in tungsten. During manufacturing of such alloys the forming properties are adversely affected by the precipitation of the intermetallic compound W₂Re₃ (σ-phase).

The purpose of this work is to clarify the influence of sigma phase on the formability and product quality after high temperature densification and thermomechanical treatment (TMT) of powder metallurgy manufactured W-25%Re alloys using different processing parameters. The study consists of two parts. Part I deals with theoretical and practical aspects on the formation of sigma phase particles and their influence on metal flow and product quality. Different ways of interpreting the W-Re phase are discussed and the characteristics of the σ-phase are presented. Practical recommendations to control the negative influence of the σ-phase are also given. A more complete understanding of the effect of various processing parameters will be the subject of Part II of this paper.