轧制变形对93WNiCu合金微观结构和力学性能的影响

选用93WNiCu高比重合金,采用冷轧的方法对其进行轧制变形处理,变形量分别为5%、10%、15%、20%,通过对变形前后材料内部组织结构的观测,分析了材料内部轧制变形机理,并对变形前后的材料进行力学性能测试,对比分析轧制变形对93WNiCu合金性能的影响。结果表明:93WNiCu合金材料经过轧制变形后内部钨颗粒呈条带状,粘结相均匀分布在钨颗粒之间;轧制变形可有效地提高合金的抗拉强度,20%变形量的轧制变形就可使材料的室温抗拉强度由烧结态的900 MPa提高到1 270 MPa,延伸率由7.6%降低到4%;通过金相以及拉伸断口显微观测,分析了93WNiCu轧制变形强化机理。     

变形量对旋转锻造钨合金组织及绝热剪切敏感性影响

对烧结态93W-4.9Ni-2.1Fe合金进行不同变形量旋转锻造,研究变形量对钨合金微观组织及绝热剪切敏感性的影响。微观组织观察结果表明,旋转锻造形变后钨颗粒沿变形方向被拉长为椭球形,随变形量由3.45%增加至42.11%,钨颗粒变形程度加剧,长径比由1.32增加至2.41;位于钨颗粒间的粘结相则沿变形方向逐渐拉长为细长的条状组织。对不同变形量的旋转锻造钨合金,沿棒料径向取样进行动态压缩试验后发现:当变形量增加至15.84%(钨颗粒长径比1.47)时,旋转锻造钨合金塑性变形方式发生改变,合金中开始出现绝热剪切现象;此后,随旋转锻造变形量(钨颗粒长径比)的增加,旋转锻造钨合金中绝热剪切带宽度减小,合金绝热剪切敏感性增大。随旋转锻造变形量(钨颗粒长径比)的增大,合金应变硬化能力减小,同时动态加载时绝热温升数值增大,软化效应增强,这是旋转锻造钨合金绝热剪切敏感性随变形量(钨颗粒长径比)增加而增大的主要原因。     

2205双相不锈钢中σ相的析出规律

2205双相不锈钢经过1300℃固溶处理和不同程度的冷轧变形后,在不同温度下保温不同时间后水冷.利用金相显微镜和透射电镜观察试样的组织,用Image Tool软件分析组织中σ相的含量,研究2205双相不锈钢中σ相的析出规律.在950℃保温,当冷轧变形量从50%增大到85%时,σ相析出时间从30 min缩短为3 min.冷轧变形量为85%的试样,在950℃保温,当保温时间从3 min延长至30 min时,σ相的体积分数从1.2%增大到11.8%.在875~950℃保温5 min后,当温度从875升高至950℃时,σ相的体积分数从8.9%降低至3.6%;在975℃保温5 min后,组织中不存在σ相.      

Mo-30Cu合金轧制变形组织及性能研究

对粉末冶金法制备的Mo-30Cu合金板材,在不同工艺条件下进行轧制试验,采用金相显微镜及扫描电镜对轧制变形后的组织进行观察,并采用维氏硬度计对经过不同道次变形量的材料进行硬度测试,研究合金的轧制变形性能及组织演变.研究发现,热轧温度为900℃、变形量达到50％时,板材试样轮廓清晰,Mo颗粒被压扁拉长,呈椭球状,烧结态组织转变为变形组织.总变形量为98％的Mo-30Cu合金箔材组织中,Mo相与Cu相均被压成纤维状,两相成均匀层叠分布,Mo层与Mo层、Mo与Cu层间界面清晰,彼此结合紧密.Mo-30Cu合金的轧制变形行为分为3个阶段:总变形量小于50％时,Mo颗粒在Cu相中滑移及Cu相变形;变形量介于50％～90％时,Mo相和Cu相协调变形:变形量大于90％时,Mo相变形.经热轧变形后的Mo-30Cu合金,当冷轧变形量为0％～ 25％时,由于加工硬化,维氏硬度呈直线上升;当冷轧变形量大于25％时,随着变形量的增加,钼骨架和铜相逐渐变形形成纤维组织,位错密度的增长趋势逐渐减弱,加工硬化效应也会逐渐低于线性增长规律,同时晶格畸变能增加,产生变形热效应,促使材料中产生回复过程,材料的硬度增加缓慢.     

WNiCu合金的变形强化研究

选用65WNiCu合金作为研究对象,进行了变形强化研究,对不同变形量的合金分别作了抗拉强度、伸长率测试,考察了变形量对合金力学性能的影响,并采用SEM观察了变形量30%时合金的微观组织形貌和室温拉伸断口。结果表明:65WNiCu合金经变形强化后钨颗粒被拉长,粘结相均匀分布在钨颗粒周围;随着变形量增加合金的抗拉强度明显增高,伸长率逐渐降低;当合金的变形量达到30%时,抗拉强度从HIP态的750MPa提高到890MPa,伸长率由18.5%降低到7.5%,实验证明变形强化对提高65WNiCu合金的抗拉强度效果明显。     

70MoCu合金室温变形行为与断裂机制

通过室温下冷轧试验, 研究了70MoCu合金（由质量分数分别为70%的Mo和30%的Cu组成）在不同变形量条件下的微观组织及力学性能. 试验得到了微观组织、力学性能随冷轧变形量的变化规律. 随着变形量的增加, 组织形貌发生显著变化, 钼颗粒沿轴向被拉长, 粘结相铜也被拉成长条状;70MoCu合金最先在Mo-Cu或Mo-Mo界面开裂, 接着是钼自身的开裂;同时, 70MoCu的硬度不断增大. 通过合金的室温拉伸试验, 对断口的观察发现70MoCu合金在室温下的断裂是粘结相Cu的撕裂, Mo-Cu界面的分离, Mo-Mo界面的分离, Mo颗粒的解理断裂等4种断裂模式共同作用的结果, 粘结相Cu的撕裂和Mo-Cu界面的分离是其主要的断裂方式.     

轧制塑性变形对W-Cu复合材料组织性能影响

对不同Cu含量[20%～50%(质量分数)]的热挤压后的W-Cu合金坯料进行轧制,通过对比得出最佳轧制工艺参数,并制备出微观组织均匀、致密度高、性能优异的W-Cu合金板材。结果表明:轧制力随着道次轧下量的增加而逐渐增大,并且当一次轧下量超过60%时,轧制力急剧增加;随着轧制变形量的增加,Cu相发生变形,W相形状基本不发生变化,但W相有细化的趋势;轧制变形能在保持W-Cu合金热挤压后高组织均匀性、高致密度、高性能的基础上获得薄板甚至是箔材。     

LD型冷轧管机轧制过程中变形及轧制压力的实验研究

通过对 LD—60型冷轧管机的现场测试以及实验数据分析,说明了 LD 型冷轧管机有它自己的变形特点。轧制过程中变形量沿宏观变形区长度上的分配,影响金属在变形工作锥上的硬化过程、轧制力参数以及变形工具的使用寿命。本文在实验研究的基础上,提出了在 LD 型冷轧管机变形区上力参数的合理分布原则,并据此提出相对减壁量沿宏观变形区长度上的分配原则。     

高比重合金变形加工研究进展

介绍旋锻、轧制、静液挤压和热等静压等形变方式对高比重钨合金的抗拉强度和延伸率的影响及研究进展,发现热静液挤压可以使钨合金材料具有较好的强化效果和较高的延伸率;研究分析了高比重钨合金的变形显微组织和断裂机制,随着变形程度的增加,钨颗粒由球形变成条形最终形成纤维组织,断裂方式则以粘结相撕裂为主导逐渐转变成以钨颗粒穿晶断裂为主。     

纯钨表面含镍涂层的浸渗法制备

为实现钨与铜的冶金可靠连接,采用浸渗法在纯钨材料表面制备一层含镍涂层。利用SEM及EDS研究不同浸渗熔体所对应的涂层/钨界面显微组织与成分分布。结果表明:于1 500℃温度通过Ni-Fe、Ni-Cu、Ni三种熔体浸渗,钨材表面对应形成的Ni-Fe涂层、Ni-Cu涂层、Ni涂层均与钨实现了冶金结合;Ni-Fe涂层对应的钨界面形成了由圆滑W颗粒相和少量粘结相组成的钨基高密度合金组织;在Ni涂层中,沿钨界面形成了厚1～2μm、由NiW和NiW2组成的化合物层。结合实验结果及W-Ni二元相图,分析了涂层/钨界面组织的形成机制。     

梯度结构W(Mo)-Ni-Fe高密度合金的组织与结构

将93W-4.9Ni-2.1Fe混合粉末压坯经过脱脂预烧、渗钼和脱钼处理以及烧结,得到W(Mo)-Ni-Fe高密度合金,采用金相分析、能谱分析、显微硬度测试等方法对该合金的成分和微观结构进行分析.结果表明,W-Ni-Fe高密度合金经渗钥处理后形成显微组织、钼含量和镍铁粘结相的梯度分布,其特征是合金表层的粘结相少于芯部:...     

微量稀土Y对细晶93W-4.9Ni-2.1Fe合金性能的影响

采用溶胶-喷雾干燥-热还原法制备了添加微量稀土Y的93W-4.9Ni-2.1Fe复合粉末,将粉末在不同温度下经不同保温时间烧结,研究了微量稀土Y对93W-4.9Ni-2.1Fe复合粉末的氧含量、合金的显微组织和性能的影响.结果表明:添加微量稀土元素Y的合金试样需要在更高的温度下才能达到理想的氧含量;微量稀土Y使合金致密度稍有降低,但使合金中钨晶粒尺寸明显细化,其作用机理主要是稀土元素抑制了液相烧结时钨晶粒的长大.     

Tensile Flow Behavior of Tungsten Heavy Alloys Produced by CIPing and Gelcasting Routes

Present work describes the flow behavior of tungsten heavy alloys with nominal compositions 90W-7Ni-3Fe, 93W-4.9Ni-2.1Fe, and 95W-3.5Ni-1.5Fe (wt pct) produced by CIPing and gelcasting routes. The overall microstructural features of gelcasting are finer than those of CIPing alloys. Both the grain size of W and corresponding contiguity values increase with increase in W content in the present alloys. The volume fraction of matrix phase decreases with increase in W content in both the alloys. The lattice parameter values of the matrix phase also increase with increase in W content. The yield strength (σ_YS) continuously increases with increase in W content in both the alloys. The σ_YS values of CIPing alloys are marginally higher than those of gelcasting at constant W. The ultimate tensile strength (σ_UTS) and elongation values are maximum at intermediate W content. Present alloys exhibit two slopes in true stress–true plastic strain curves in low and high strain regimes and follow a characteristic Ludwigson relation. The two slopes are associated with two deformation mechanisms that are occurring during tensile deformation. The overall nature of differential curves of all the alloys is different and these curves contain three distinctive stages of work hardening (I, II, and III). This suggests varying deformation mechanisms during tensile testing due to different volume fractions of constituent phases. The slip is the predominant deformation mechanism of the present alloys during tensile testing.     

Effect of dissolved tungsten on the deformation of 70Ni-30Fe alloys

A series of Ni-Fe alloys containing various levels of tungsten in solid solution have been prepared as a means to assess the influence of solid solution strengthening on the mechanical behavior of monolithic 70Ni-30Fe. In particular, 70Ni-30Fe alloys plus equilibrium concentrations of tungsten in solid solution nominally correspond to the compositions associated with the matrix-only portion of certain tungsten heavy alloys, that is, alloys comprised of a high volume fraction of nominally pure tungsten particles embedded within a minority Ni-Fe-W based matrix. The study shows that the working solubility of tungsten within the 70Ni-30Fe base composition increases slightly with temperature, from approximately 21 wt pct at room temperature to approximately 23 wt pct at 1400 °C. Increasing the level of tungsten in solid solution leads to increases in room-temperature yield strength, tensile strength, and ductility. In contrast, the deformation characteristics of the alloys, as quantified by the power-law work-hardening exponent, n, and the strain-rate-sensitivity exponent, m, show little variation with tungsten solute concentration.     

冷轧变形量对304不锈钢力学性能的影响

 研究304奥氏体不锈钢薄板的硬度随冷轧变形量的变化规律,为奥氏体不锈钢薄板工业生产提供指导。同时,采用金相显微镜、维氏硬度测量、X-射线衍射仪和透射电镜研究了不同变形量冷轧对304不锈钢显微组织和机械性能的影响。在室温对0.5mm厚退火板材进行冷轧,使冷轧变形量从10%增加到52%。结果表明,形变诱发马氏体相变是导致304不锈钢冷轧时产生加工硬化的主要原因,冷轧可以显著提高钢的强度和硬度。当冷轧变形至40%时,304不锈钢的维氏硬度是未变形时的2.2倍,屈服强度、抗拉强度分别增大到未变形时的4.2倍（880MPa）和1.8倍（1312MPa）。     

纳米Y2O3 对97W-2Ni-Fe 合金组织与性能的影响

以W、Ni、Fe元素粉末和纳米Y₂O₃粉末为原料,制备97W-2Ni-1Fe和96.5W-2Ni-Fe-0.5Y₂O₃钨合金,通过扫描电镜(SEM)、能谱仪(EDS)等手段进行表征,并结合黏结相的面积分数和W晶粒接触度的分析,研究烧结温度与添加纳米Y₂O₃对高密度钨合金微观组织与力学性能的影响。结果表明:随烧结温度升高,钨合金的晶粒尺寸和力学性能明显增加。在1510℃(液相)烧结温度下,添加纳米Y₂O₃使钨晶粒尺寸从21.6μm减小至7.8μm,黏结相的面积分数从4.45%增加至5.35%,接触度为0.67,合金力学性能显著提升,抗拉强度达到611 MPa,硬度(HRC)为40.1。96.5W-2Ni-Fe-0.5Y₂O₃合金的拉伸断裂形态为黏结相的撕裂和少量W晶粒解理断裂,添加纳米Y₂O₃使得黏结相撕裂的比例增加。     

Structural changes in the surface of titanium carbide and tungsten carbide hard alloys with nickel binder upon exposure to laser radiation

Pulsed laser action on cemented titanium carbide with nickel—chromium binder yields deep changes in its structure; and in the case of cemented tungsten carbide with nickel binder, the structural change is accompanied by phase transformations in the heat-affected zone. As a result of these changes, layers with thickness 30–60 µm and 30–60% greater hardness are formed. When the energy density of the laser radiation is higher than 200 J/cm², thermal failure of cemented carbide surfaces occurs (observed as crack formation).     

The creep behavior of W-5 re

Polycrystalline W-5 wt pct Re was creep-tested in tension from 1500° to 1900°C at stresses from 2500 to 10,000 psi in a vacuum of 10^?8 torr. The steady-state strain rate was directly proportional to stress to the 5.5 power, and the apparent activation energy for creep was 104 kcal per mole. Dislocation substructure that developed during high-temperature deformation was studied by transmission electron microscopy. The total dislocation density was dependent on stress to the 2.1 power and was insensitive to temperature and strain. No subgrains were found in creep tested specimens. The rate-controlling deformation mechanism was ascribed to dislocation climb where the governing diffusion process was dislocation core diffusion. Comparison of creep data for tungsten, W-5 wt pct Re, and W-25 wt pct Re showed that W-5 wt pct Re alloy has significantly better creep properties than the other two materials.