快速-热挤压工艺对细晶和传统钨合金组织与性能的影响

研究了快速-热挤压工艺对细晶93W-4.9Ni-2.1Fe、细晶93W-4.9Ni-2.1Fe+0.03%Y以及传统粗晶93W-4.9Ni-2.1Fe合金的显微组织和力学性能的影响。结果表明：经过快速热挤压后,合金的综合力学性能较烧结态合金显著提高,而且初始晶粒尺寸对挤压后合金性能影响非常显著,在相同的挤压条件下,挤压态细晶93W-4.9Ni-2.1Fe+0.03%Y的抗拉强度达到1570 MPa,延伸率为6.5%,硬度HRC45.2;而挤压态传统93W-4.9Ni-2.1Fe合金的抗拉强度、延伸率和硬度分别只有1260 MPa、5.6%和39.1。显微组织观察分析表明,与传统钨合金相比,在相同变形量的情况下,细晶93W-4.9Ni-2.1Fe+0.03%Y钨合金的纤维化程度更高,钨颗粒长细比达到6.8。TEM观察表明挤压后细晶钨合金的钨相形成了亚晶组织,而传统钨合金有大量位错缠结于钨相中;此外,由于充分的动态回复-再结晶,细晶和传统钨合金的粘结相位错密度很低。     

快速-热挤压工艺对细晶和传统钨合金组织与性能的影响

研究了快速-热挤压工艺对细晶93W-4.9Ni-2.1Fe、细晶93W-4.9Ni-2.1Fe+0.03%Y以及传统粗晶93W-4.9Ni-2.1Fe合金的显微组织和力学性能的影响。结果表明:经过快速热挤压后,合金的综合力学性能较烧结态合金显著提高,而且初始晶粒尺寸对挤压后合金性能影响非常显著,在相同的挤压条件下,挤压态细晶93W-4.9Ni-2.1Fe+0.03%Y的抗拉强度达到1570MPa,延伸率为6.5%,硬度HRC45.2;而挤压态传统93W-4.9Ni-2.1Fe合金的抗拉强度、延伸率和硬度分别只有1260MPa、5.6%和39.1。显微组织观察分析表明,与传统钨合金相比,在相同变形量的情况下,细晶93W-4.9Ni-2.1Fe+0.03%Y钨合金的纤维化程度更高,钨颗粒长细比达到6.8。TEM观察表明挤压后细晶钨合金的钨相形成了亚晶组织,而传统钨合金有大量位错缠结于钨相中;此外,由于充分的动态回复-再结晶,细晶和传统钨合金的粘结相位错密度很低。     

真空烧结制备90W-Ni-Fe高密度钨合金的性能与显微结构

采用真空烧结法制备90W-7Ni-3Fe高密度钨合金,通过材料试验机、SEM、XRD等表征了材料的性能与显微结构。结果表明:钨合金的相对密度、强度、塑性均随烧结温度升高先上升后下降,1 440℃烧结试样的性能最佳,其相对密度、抗弯强度、抗拉强度、伸长率和断面收缩率分别为99.2%、1 920.5 MPa、1 086.7 MPa、22.8%和24.4%。钨合金单纯由体心立方的钨相和面心立方的Fe3Ni2固溶体相组成,未出现其他杂质相。在1 360~1 460℃的烧结温度范围内,随温度的升高,钨合金断裂形态依次发生以下转变:沿晶脆性断裂、穿晶脆性断裂、韧窝韧性断裂、粘接相撕裂韧性断裂和穿晶脆性断裂。     

放电等离子烧结制备9Cr-ODS钢的组织与力学性能

采用放电等离子烧结(Spark plasma sintering,SPS)工艺制备了成分为Fe-9Cr-1.5W-0.4Mn-0.2V-0.1Ta-0.3Ti-0.3Y_2O_3(质量分数,%)的9Cr-ODS钢。利用扫描电镜(SEM)、透射电镜(TEM)、电子背散射衍射(EBSD)、高分辨透射电镜(HRTEM)对ODS钢的宏观烧结特征、晶粒形貌、析出相形貌等进行表征。利用万能拉伸试验机测量不同温度下样品的力学性能。结果表明:通过放电等离子体烧结工艺可以制备出具有超细晶粒的ODS钢,950℃/5 min时烧结效果最好,致密度达到97.7%。950℃/5 min烧结后样品的晶粒呈现粉末颗粒表面晶粒粗大(1μm)而内部晶粒细小(纳米级)的现象,样品内的析出相以高密度、纳米尺寸、弥散分布的纳米团簇为主,其分布密度可以达到5.1×10~(22)个/m~3,同时还发现了少量化学计量比的Y_2Ti_2O_7。放电等离子体950℃/5 min烧结样品的常温和650℃拉伸强度分别达1040 MPa和407 MPa。     

SPS循环热处理对93W-4.9Ni-2.1Fe合金组织和性能的影响

基于放电等离子烧结(SPS)技术对烧结态的93W-4.9Ni-2.1Fe高密度钨合金进行真空循环热处理,并通过光学显微镜、SEM、EDS和三点弯曲实验分析循环热处理对合金的显微组织、成分和力学性能的影响规律。结果表明,随着循环次数的不断增加,粘结相渗入W-W界面不断增多,W-W连接度和二面角不断降低,而钨晶粒尺寸变化较小;粘结相则因W含量的增加得到了固溶强化,进而致使合金的硬度有所提高。合金的抗弯强度在循环2次后明显提高,当循环次数增加到20次后,合金的平均抗弯强度达到2321 MPa,相比液相烧结后淬火处理的合金提高了约160 MPa。因此,SPS循环热处理可以明显改善93W-4.9Ni-2.1Fe高密度钨合金的组织和力学性能。     

放电等离子烧结W-Ni-Mn合金的显微组织演变及力学性能（英文）

以微米级的钨粉、镍粉和锰粉为原料,将原料混合均匀后进行放电等离子烧结(SPS)制备90W-6Ni-4Mn合金,探究SPS烧结温度对90W-6Ni-4Mn合金显微组织演变和力学性能的影响。研究结果表明,利用放电等离子烧结(SPS)方法可以在1150~1250°C温度下保温3 min制备出近全致密、综合性能优良的90W-6Ni-4Mn合金。分析合金显微组织,90W-6Ni-4Mn合金组织均匀,平均晶粒尺寸均在10μm以下,主要由钨基相和γ-(Ni,Mn,W)粘结相组成。力学性能测试表明,提高烧结温度,合金的洛氏硬度以及抗弯强度均呈先增大后减小的趋势,在1200°C时其硬度为HRA 68.7,抗弯强度达1162.72 MPa,综合性能最好。     

W-(Ni-Cr-Fe-Si-B)混合粉末中间层真空扩散钎焊连接钨与钢

以高能球磨态90W-10(Ni-Cr-Fe-Si-B)(质量分数,%)混合粉末为钎料中间层,分别采用1000、1050和1100℃,均保温60 min并加压5 MPa的工艺参数,对纯钨(W)和0Cr13Al钢进行真空扩散钎焊连接。利用激光粒度分析仪、SEM、EDS和电子万能试验机等研究混合粉末形态、接头的微观组织、成分、力学性能及断口特征。结果表明:接头中的混合粉末中间层通过液相烧结过程,实现钨与钢的扩散钎焊连接,并在接头中生成均匀致密的钨基高密度合金层。高能球磨制备混合粉末对钨基高密度合金层压力下的均匀化与致密化生成具有关键作用。连接温度越高,钨基高密度合金层的液相烧结组织特征越明显。钨/钢接头剪切强度在125~130 MPa之间,断裂均发生在钨基高密度合金层/钨母材的结合区,断口主要呈现为钨母材的脆性沿晶断裂和钨基高密度合金层粘结相与钨颗粒相的韧性脱离断裂。     

放电等离子烧结温度对钨合金的组织及动态力学性能的影响

以纳米93W-4.9Ni-2.1Fe 合金粉末为原料,研究放电等离子烧结温度对钨合金组织和动态力学性能的影响。结果表明,采用放电等离子烧结方法可制备出组织均匀的细晶钨合金。当烧结温度在950~1400 ℃时,随着烧结温度的增加,钨颗粒平均尺寸由2 μm增大到10 μm,试样动态抗压强度随之降低;动态压缩过程中,烧结温度在1000~1200 ℃的试样塑性均较好,而当烧结温度超过1300 ℃时,试样的塑性很低,表现为明显的脆性状态     

添加Cr元素对93W-4.9Ni-2.1Fe合金微观结构和性能的影响

以高能球磨粉末为原料,研究了铬元素对93W-4.9Ni-2.1Fe合金性能和微观结构的影响.实验采用光学金相(OM)、扫描电镜(SEM)、EDAX能谱等方法对试样的组织形貌进行了表征;对合金的拉伸强度、延伸率和合金的相对密度进行了测试.结果表明:不添加Cr的93W-4.9Ni-2.1Fe合金其相对密度为99.3%,延伸率为15%,抗拉伸强度为997.2 MPa;在Cr的添加量 (质量分数)为0～1.5%,随Cr含量由0增加到1.5%,93W-Ni-Fe合金抗拉伸强度、相对密度、延伸率分别由997.2 MPa、99.3%、15%降至834.7 MPa、95.2%、5.7%;添加Cr元素后,Cr、W、Ni、Fe、O等元素在93W-Ni-Fe合金中生成富Cr固溶体,并在合金界面上形成偏聚,降低了93W-Ni-Fe合金界面的结合强度,导致合金的力学性能有所降低.     

微量Cr对93W-Ni-Fe合金组织及力学性能的影响

研究了Cr元素对93W-4.9Ni-2.1Fe高密度合金性能和微观结构的影响,并探讨固溶淬火工艺对添加微量Cr的93W-Ni-Fe合金微观结构及力学性能的影响.实验采用光学金相、扫描电镜和能谱等对烧结态、固溶淬火态样品的组织形貌进行表征,采用准静态拉伸实验对合金的拉伸强度和伸长率进行测试,采用阿基米德排水法对合金的相对密度进行测试.结果表明:随着Cr含量(质量分数)由0增加到1.5%,烧结态93W-Ni-Fe合金的拉伸强度、相对密度、伸长率分别由997.2 MPa、99.27%和14.94%降至834.7 MPa、95.21%和5.69%.随着Cr含量由0增加到1.5%,固溶淬火态93W合金的拉伸强度、相对密度、伸长率分别由1 039 MPa、99.33%和18.37%降至888.5MPa、96.10%和7.39%;Cr元素与W、Ni、Fe、O等元素在93W-Ni-Fe合金中生成富Cr固溶体,并在合金界面上形成偏聚,降低93W-Ni-Fe合金界面的结合强度,导致合金的力学性能降低.     

直接能量沉积Ti-XV-15Cr(X=20,25,30,35)合金的组织和阻燃性能

使用直接能量沉积技术,以纯Ti、纯V和纯Cr粉末为原料制备一系列Ti-YV-15Cr(X=20,25,30,35)合金.研究了V含量对Ti-XV-15Cr合金的晶粒形貌、显微硬度、弹性模量及阻燃性能的影响.结果表明,Ti-20V-15Cr、Ti-25V-15Cr和Ti-30V-15Cr合金的显微组织由外延生长的柱状晶和...     

放电等离子烧结时间对高密度W-7Ni-3Fe合金组织性能的影响

利用放电等离子烧结技术制备高密度W-7Ni-3Fe合金,研究了烧结保温时间对合金致密度、物相、显微组织以及力学性能的影响。结果表明,在1200℃烧结5~14 min后,合金均能实现充分致密化,保温时间对相对密度影响较小。合金中的W晶粒随保温时间的延长开始尺寸变化不大,烧结11 min以上才明显长大,但大多数W晶粒尺寸仍小于5μm。烧结时间超过8min,合金中新出现一种灰色的富W组织。随保温时间延长,合金的洛氏硬度下降不大,然而抗弯强度却明显上升。合金弯曲断口形貌在较短保温时间以沿晶断裂为主,粘结相的延性撕裂和W晶粒的解理断裂随烧结时间延长逐渐增多。     

Microstructural control of and mechanical properties of mechanically alloyed tungsten heavy alloys

93W-5.6Ni-l.4Fe tungsten heavy alloys with controlled microstructures were fabricated by mechanically alloying of elemental powders of tungsten, nickel and iron by two different process routes. One was the full mechanical alloying of blended powders with a composition of 93W-5.6Ni-l.4Fe, and the other was the partial mechanical alloying of blended powders with a composition of 30W-56Ni-14Fe followed by blending with tungsten powders to form a final composition of 93W-5.6Ni-l.4Fe. The raw powders were consolidated by die compaction followed by solid state sintering at 1300°C for 1 hour in a hydrogen atmosphere. The solid state sintered tungsten heavy alloys were subsequently liquid phase sintered at 1445∼1485°C for 4-90 min. The two-step sintered tungsten heavy alloy using mechanically alloyed 93W-5.6Ni-l.4Fe powders showed tungsten particles of about 6-15 μm much finer than those of 40 um in a conventional liquid phase sintered tungsten heavy alloy. An inhomogeneous distribution of the solid solution matrix phase was obtained in the two-step sintered tungsten heavy alloy using partially mechanically alloyed powders. The two-step sintered tungsten heavy alloy using mechanically alloyed 93W-5.6Ni-l.4Fe powders showed larger elongation of 16% than that of 1% in the solid state sintered tungsten heavy alloy due to the increase in matrix volume fraction and decrease in W/W contiguity. Dynamic torsional tests of the two-step sintered tungsten heavy alloys showed reduced shear strain at maximum shear stress than did the sintered tungsten heavy alloys using the conventional liquid phase sintering.     

Impact and dynamic deformation behavior of mechanically alloyed tungsten heavy alloy

93W-5.6Ni-l.4Fe tungsten heavy alloy was fabricated by mechanical alloying process using elemental powders of tungsten, nickel and iron, followed by sintering at temperatures of 1445~1485°C under hydrogen atmosphere. The tungsten heavy alloy sintered using mechanically alloyed powders showed finer tungsten particles about 5~18 μm with high density above 99% at shorter sintering time than that fabricated by conventional liquid-phase sintering process. Charpy impact energy of mechanically alloyed tungsten heavy alloy increased with increasing the matrix volume fraction and with decreasing the W/W contiguity. The high strain rate dynamic deformation behavior of tungsten heavy alloys using torsional Kolsky bar test exhibited different fracture modes dependent on microstructure. While the brittle intergranular fracture mode was dominant when the tungsten particles were contiguously interconnected in tungsten heavy alloys solid-state sintered below 1460°C, the ductile shear fracture mode was dominant when the tungsten particles were surrounded by ductile matrix phase in tungsten heavy alloys liquid-phase sintered above 1460°C.     

钾掺杂钨合金中气相热充氘的热脱附行为

钾(K)掺杂钨(W)合金已经表现了优异的高温力学性能,成为最有希望的PFMs 备选材料之一.为评估氢同位素在W-K合金中的滞留情况,采用放电等离子烧结技术(SPS),制备了纯W及K含量82 μg/g 的W-K 合金,通过气相热充法引入氘(D)元素,考察热脱附行为.研究表明,气相热充氘释放温区从600 K 延伸至1200...     

Microstructure of tungsten metal alloys produced by Field Assisted Sintering Technology (FAST)

Tungsten (W) refractory alloys are of high importance in the development of high temperature application products seen in furnace elements, the aerospace industry, and many other areas. Traditional manufacturing processes produce tungsten alloys with undesirable mechanical properties due to a large grain microstructure. Commercial sintering techniques yield low density products due to the poor sinterability of tungsten alloys. Field Assisted Sintering Technology (FAST) is used in this work to produce tungsten alloys with high density, and acceptable microstructures. Limited research has been done with hafnium carbide (HfC) as grain growth inhibitors. 100% W, W-1vol%HfC, W-2vol%HfC, and W-5vol%HfC were sintered at 2100 °C, 35 MPa, for 25 min. Microstructure of each composition was characterized and reported. For volume additions of 2% or more of hafnium carbide shows a decrease in grain size of over 67% while increasing the hardness by over 19% when compared with a pure tungsten composition. These results include imaging between the W-HfC interfaces gathered from high resolution transmission electron microscopy (HRTEM).     

SPS烧结W-10Ti合金的组织和性能

采用放电等离子烧结(SPS)技术制备了W-10Ti合金。通过扫描电镜和能谱分析了合金的微观组织,利用Den Broeder方法计算了合金的互扩散系数,测试了合金的密度和显微硬度,并与真空烧结的合金进行了对比。结果表明:与真空烧结相比,SPS烧结的合金组织均匀,富钛相少且细小,W在富钛相中的固溶度和Ti在富钨相中的固溶度都有所增加,且Ti在富钨相中的固溶度增加得更多。W-Ti合金的互扩散系数与W的摩尔浓度有一定的依赖关系,随着W摩尔浓度的升高呈先减小后增大趋势,SPS烧结的合金互扩散系数比真空烧结高出2个数量级。SPS法制备的W-Ti合金相对密度为96.1%,显微硬度HV0.05为5.21 GPa。     

Properties and microstructural evolution of W-Ni-Fe alloy via microwave sintering

The mechanical properties and microstructure evolution of 93W-4.9Ni-2.1Fe (wt.%) alloys were investigated via microwave sintering. The microwave sintering promoted the dissolution and diffusion of tungsten atoms in the matrix phase and strengthened sintering activity. With the increase of microwave sintering temperature, pores in the alloy were reduced and gradually eliminated, tungsten grains coarsened, the distribution of tungsten grains and matrix phase became more homogeneous, and the fracture mode transformed from intergranular fracture to tungsten transgranular cleavage fracture, respectively. The W-matrix interfacial bond strength of 93W-4.9Ni-2.1Fe was enhanced and the mechanical properties were significantly improved with the increase of sintering temperature.     

A comparative study of spark plasma sintering and hybrid spark plasma sintering of 93W–4.9Ni–2.1Fe heavy alloy

Mixed 93W–4.9Ni–2.1Fe powders were sintered via the spark plasma sintering (SPS) and hybrid spark plasma sintering (HSPS) techniques with 30 mm and 60 mm samples in both conditions. After SPS and HSPS, the 30 mm and 60 mm alloys (except 60 mm-SPS) had a relative density (> 99.2%) close to the theoretical density. Phase, microstructure and mechanical properties evolution of W–Ni–Fe alloy during SPS and HSPS were studied. The microstructural evolution of the 60 mm alloys varied from the edge of the sample to the core of the sample. Results show that the grain size and the hardness vary considerable from the edge to the core of sintered sample of 60 mm sintered using conventional SPS compared to hybrid SPS. Similarly, the hardness also increased from the edge to the core. Furthermore, the 60 mm-HSPS alloy exhibited improved bending strength of 1115 MPa when compared to that of 60 mm-SPS, 920 MPa. The intergranular fracture along the W/W grain boundary is the main fracture modes of W–Ni–Fe, however in the 60 mm-SPS alloy peeling of the grains was also observed which diminished the properties. The mechanical properties of SPS and HSPS 93W–4.9Ni–2.1Fe heavy alloys are dependent on the microstructural parameters such as tungsten grain size and overall homogeneity.