烧结温度对W-10Ti合金显微组织和硬度的影响

以W粉和Ti粉为原料,采用真空热压烧结工艺制备了W-10%Ti合金,研究了烧结温度对W-Ti合金的相组成、微观形貌和硬度的影响。结果表明,合金主要由富W固溶体、富Ti固溶体和心部未发生扩散的α-Ti相组成。随烧结温度的升高,W与Ti的相互固溶度增大,α-Ti相的残余量减少,1400℃烧结的W-Ti合金中部分富Ti固溶体发生了共析转变。合金的致密度和维氏硬度均随烧结温度的升高先增大后减小,在1300℃时有最大值,分别达99.4%和6.3 GPa。     

原料粉末对SPS烧结W10Ti合金组织及性能的影响

分别采用两类粉末为原料:一类粉末是将球磨前后的W和钛源Ti或TiH_2进行机械混合,另一类粉末是将未球磨的W粉和钛源TiH_2粉进行机械合金化。之后选用SPS烧结技术(spark plasma sintering)来制备W-10Ti合金。通过XRD、SEM、纳米压痕等检测手段研究了原料粉末对W-10Ti合金组织及性能的影响。结果表明:较未球磨W粉,采用球磨W粉所制备的WTi合金组织中无纯钛相,且富钛相含量减少了44%,同时合金的纳米硬度提高了55.7%。细小、均匀的TiH2粉末有利于获得富钛相较少、均匀、细小的微观组织,用其制备的WTi合金致密度高达100%。相比使用Ti粉来制备W-10Ti合金,TiH2粉制备的合金电导率、纳米硬度和弹性模量分别提高了7%、46%和34%。而采用机械合金化粉末所制备的合金中条状的富钛相增多,组织更为细小,且该合金的韧性较好,但其致密度及纳米硬度均较低,分别仅为96.8%和2.8 GPa。因此,SPS烧结使用的粉末状态是制备高性能WTi合金的关键因素。     

机械合金化W-Ti粉末的烧结特性

用高能球磨法制备了W-Ti预合金粉末,研究了纳米晶W-Ti粉末的真空烧结致密化和显微组织演化现象以及热处理时组织形貌的变化,并与未球磨粉末的烧结试样进行了比较。结果表明,提高烧结温度有利于提高相对密度;1500℃,2 h为最佳烧结工艺。机械合金化导致粉末内晶粒纳米化,形成成分不均的固溶体W-Ti粉末,使真空烧结后的显微组织结构明显细化,相对密度显著提高;扩散退火后能够形成成分较均匀的W-Ti固溶体。     

SPS循环热处理对93W-4.9Ni-2.1Fe与95W-2.8Ni-1.2Fe-1Al_2O_3合金组织及性能的影响

利用放电等离子烧结(SPS)技术对具有相同理论密度的烧结态93W-4.9Ni-2.1Fe和95W-2.8Ni-1.2Fe-1Al_2O_3高密度钨合金进行循环热处理,并通过光学显微镜、SEM、TEM、EDS和三点弯曲实验分析循环热处理对两种合金显微组织和力学性能的影响规律。结果表明:随着SPS循环热处理次数的增加,93W-4.9Ni-2.1Fe合金在平均W晶粒尺寸未发生明显变化的同时,其粘结相中的W含量和位错密度不断升高,合金得到了固溶强化与位错强化,合金的硬度、抗弯强度、断裂挠度等性能相应提高;而对于95W-2.8Ni-1.2Fe-1Al_2O_3合金,由于更高的W含量和Al_2O_3颗粒的加入,烧结态时具有小得多的平均W晶粒尺寸、更大的W-W连接度和高硬脆特性,且SPS循环热处理对其组织和成分分布的均匀性影响程度相对较小,其力学性能虽然随SPS循环热处理次数的增加也得到了一定程度改善,抗弯强度和断裂挠度明显较93W-4.9Ni-2.1Fe合金的低,硬度则明显高于93W-4.9Ni-2.1Fe合金硬度。但循环热处理次数过多,反而会降低两种钨合金的硬度和断裂挠度。     

钨/钛/MA956钢SPS扩散连接的界面结构和力学性能

在950℃/10MPa的工艺条件下,采用高效的放电等离子烧结技术对钨/钛/MA956进行真空扩散连接。焊后通过显微硬度测试和剪切强度试验评估SPS扩散连接的接头力学性能;并利用扫描电镜、能谱仪以及X射线衍射仪对接头的界面组织和断裂特征进行观察分析。结果表明,该技术成功实现了W/Ti/MA956在10～30min的保温时间下的可靠连接。钨/钛/MA956钢接头界面由W-Ti固溶体层、Ti层以及Ti/MA956金属间化合物(FeTi、Fe2Ti和Cr2Ti)层组成。Ti/MA956界面由于金属间化合物的生成,具有最高的硬度,硬度峰值达580HV。随着保温时间的增加(10、20、30min),接头平均剪切强度由130.2MPa(10min)提高到163.5MPa(20min)再降到125MPa(30min);接头断裂均发生在Ti/MA956界面。     

磁控溅射沉积W-Ti薄膜的结构与性能

采用复合靶磁控共溅射方法在p型(100)单晶硅衬底上制备了不同Ti含量的W-Ti薄膜,并与纯W和纯Ti薄膜作对比。采用XRD、SEM、AFM、显微硬度计和四探针电阻仪对薄膜的结构、成分及性能进行分析表征。结果表明,W-Ti薄膜呈细晶粒多晶结构,Ti含量较低时,W-Ti薄膜呈体心立方相结构,存在W基W(Ti)固溶体。Ti含量较高时,还出现hcp富Ti相。W-Ti薄膜的显微硬度随Ti含量的增加先增后减,而电阻率则随Ti含量的增加而增大。W-Ti薄膜显微硬度均高于纯Ti薄膜,电阻率则高于纯W而低于纯Ti薄膜。     

添加微量TiC对钨的性能与显微组织的影响

为细化钨晶粒,采用粉末冶金方法通过添加加量Ti C于钨基体中制备W-Ti C合金,研究了微量Ti C的添加对钨性能与显微组织的影响。结果表明:当Ti C的添加量为1%(质量分数),烧结温度为1890℃时,W-Ti C合金具有最佳性能,其拉伸强度可达401 MPa,致密度为97.4%;添加的Ti C粉末以球状二次相粒子形式分布于晶界和晶内,与纯钨相比,Ti C的添加有效地抑制了晶粒长大,对钨基体起到细晶强化与弥散强化作用。     

深冷处理对WTi10合金组织和性能的影响

对固相烧结的WTi10合金在–196℃下进行了深冷处理。对合金的显微硬度、XRD物相、SEM及TEM形貌等进行了分析和表征。结果表明:深冷处理后,合金的组成依然为富钨相和富钛相;随深冷时间的增加,钨钛合金组织中富钛相所占面积比例先增大后减小,24 h深冷处理后组织中富钛相的比例与未处理试样的差别不大;合金的晶粒尺寸也呈现先增大后减小的变化趋势,24 h后晶粒尺寸最大减小了24.6%;晶粒尺寸分布更加均匀。深冷处理能显著提高WTi10合金的显微硬度和致密度,深冷处理24 h后合金的显微硬度大约是深冷前的2.5倍;深冷24 h后合金的择优取向由(110)变为(110)和(200)。     

烧结气氛对Ti(CN)基金属陶瓷组织和性能的影响

用X射线衍射、背散射扫描电镜及能谱仪等分析手段研究了烧结气氛(真空、N2、Ar)对不同成分TiC基和Ti(CN)基金属陶瓷合金显微组织和性能的影响.金属陶瓷在N2和Ar中烧结后,合金碳含量比在真空中烧结的碳含量低0.5%左右;在N2中烧结后,合金的氮含量提高了0.5%左右.环状结构心部可以是以钨等重金属元素为主要成分的碳化物,也可以是以钛为主要成分的碳化物和碳氮化物.环状结构为金属元素含量和分布不同的(Ti,W,Ta,Mo,Co,Ni)(C,N)固溶体,粘结相是与Ti,W,Ta,Mo,C,N等元素有不同溶解度的钴镍固溶体.真空烧结后组织结构比较均匀,合金的性能最好.在Ar、N2中烧结后,气氛中的氧和氮参加烧结反应,影响合金成分碳氮平衡,在合金表面形成壳层结构,产生表面缺陷,合金的密度、显微硬度、抗弯强度均有比较大的降低;N2气氛影响更大.     

机械合金化对W-Ti合金组织与性能的影响

以乙醇为过程控制剂,采用机械球磨方法制备W-10%Ti(质量分数)、W-10%TiH2纳米晶W-Ti粉末,晶粒粒径为30～80 nm,粉体经压制后在1 823 K保温烧结80 min得到W-Ti合金.利用X射线衍射、透射电镜和扫描电镜等于段,研究球磨时间对两种粉未及其烧结试样的相组成和微观组织的影响;测量烧结试样的密度和显微硬度.结果表明:机械合金化能够降低烧结温度,提高烧结体的密度,组织均匀且晶粒细小;利用W-TiH2球磨粉制备的W-Ti合金与W-Ti粉相比密度较高且晶粒细小.     

The Effect of Sintering Temperature on Mechanical and Electrical Properties of a W-10Ti Alloy Prepared by Hot Press Sintering

W-10Ti alloy was prepared by hot press sintering using W-TiH₂ powders milled for 24 h under argon atmosphere. The effect of sintering temperature on the phase constituents and the microstructure of the alloys was characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The microhardness of W-rich phase, electrical resistivity and impurity (C, O) contents of W-10Ti alloy were determined. The results show that the amount of W-Ti solid solution, the microhardness of the W-rich solid solution and the resistance of W-10Ti alloy increase with an increase of sintering temperature. At 1300 °C, W-10Ti alloy has the maximum microhardness value of 333 HV_0.05, the O content of 360 ppm and C content of 200 ppm.     

Microstructures and Properties of W-Ti Alloys Prepared Under Different Cooling Conditions

W-(10 to 15) wt.% Ti alloys were sintered at 1400 or 1500 °C and cooled under different cooling conditions. The microstructures and properties of W-Ti alloys were affected by the cooling conditions. XRD, SEM, EBSD, and TEM were carried out to investigate the effects of cooling conditions and sintering temperature on the microstructures of W-Ti alloys. The nanohardness and elastic modulus of the alloys were also investigated. The results showed that when the temperature was 1500 °C, the content of Ti-rich phase in W-(10 to 15) wt.% Ti alloys decreased obviously with the increase of cooling rate (the average cooling rate of furnace cooling, air cooling and water cooling was 0.2, 10, and 280 °C/s, respectively). For the W-10 wt.% Ti alloy, the content decreased from 20.5 to 9.7%, and the grain size decreased from 2.33 to 0.67 μm. When the temperature decreased to 1400 °C, the grain size was also decreased sharply with the increase of cooling rate, but there was a little change in the microstructure. Meanwhile, the grain sizes were smaller than those of the alloys sintered at 1500 °C. The nanohardness and elastic modulus increased with the increase of cooling rate, and the alloys sintered at different temperatures had different nanohardness and elastic modulus which depended on the cooling conditions. Sintering at a proper temperature and then cooling at a certain cooling condition was a useful method to fabricate alloy with less Ti-rich phase and high properties.     

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.     

放电等离子体烧结制备钨-钒-铬合金及性能表征

利用机械球磨、放电等离子体烧结法制备了质量分数(%,下同)为W-(10~30)V-(10~30)Cr的三元合金,对烧结后的合金进行了显微结构和室温力学性能研究。结果表明,采用放电等离子体烧结可以制得相对密度为99.7%的W-30V-20Cr合金,其实际密度比烧结纯钨降低了49.74%;显微结构分析表明V、Cr可以很好地合金化,形成塑性连续相,包裹在钨分散相的周围,很好地改善了钨合金的力学性能,W-30V-20Cr的抗弯强度为437.13 MPa,比烧结纯钨增加了25%,HV硬度为6154 MPa;W-30V-20Cr合金具有较高的断裂韧性值,为15.51 MPa·m1/2。     

Fabrication of nano-crystalline W-Ni-Fe alloy with Mo and rare earth element additives

Three kinds of nano-crystalline high density alloys (86W-7Ni-3Fe-4Mo, 90W-4Ni-2Fe-4Mo and 90W4Ni-2Fe-3.8Mo-0.2RE) were fabricated by a technique combining lower temperature vacuum sintering with highenergy ball milling mechanical alloying. The crystalline size and microstructures of the specimens sintered at different sintering temperatures were examined by X-ray diffraction(XRD) and scanning electron microscope(SEM). The results show that the optimal sintering temperature of 86W-7Ni-3Fe-4Mo, 90W-4Ni-2Fe-4Mo and 90W-4Ni-2Fe-3.8Mo-0.2RE alloys are 1 300 - 1 350℃. When they are sintered at 1 300℃ for 75 min， the hardness of three kinds of specimens can reach above HRC30, the relative density can reach above 96%, and 90W-4Ni-2Fe-3.8Mo-0.2RE alloy possesses the best integrated properties, its hardness is HRC35 and its relative density is 98%.     

WTi10合金的高温高压制备及相特征

采用高温高压工艺制备了WTi10合金.使用电子探针、扫描电子显微镜及X射线衍射仪等手段研究制备工艺对合金密度及微观组织的影响,尤其是合金中的相演变特征.评价靶材对合金相的要求,并据此获取优化的制备工艺.研究表明,温度是制备WTi10合金密度的主要影响因素,合金的密度随温度升高而增大;温度高于1250℃的合金中为完全固溶...     

Effect of ball milling time on microstructures and mechanical properties of mechanically-alloyed iron-based materials

The microstructures and mechanical properties of an iron-based alloy (Fe-13Cr-3W-0.4Ti-0.25Y-0.30O) prepared by mechanical alloying were investigated with scanning electron microscope, optical microscope, X-ray diffractometer and hardness tester. The results show that the particle size does not decrease with milling time because serious welding occurs at 144 h. The density of the alloy sintered at 1 523 K is affected by the particle size of the powder. Finer particles lead to a high sintered density, while the bulk density by using particles milled for 144 h is as low as 70%. In the microstructures of the annealed alloy, large elongated particles and fine equiaxed grains can be detected. The elongated particle zone has a higher microhardness than the equiaxed grain area in the annealed alloys due to the larger residual strain and higher density of the precipitated phase.     

合金化元素Ti对Laves相Cr_2Nb力学性能及耐蚀性的影响

采用真空非自耗电弧熔炼工艺制备了Cr2Nb-XTi(X=5,10,15,at%)合金,利用光学显微镜(OM),X射线衍射(XRD)仪,扫描电镜(SEM)对电弧熔炼态铸锭的组织进行了研究,探讨了合金化元素Ti的含量对Laves相Cr2Nb力学性能及耐蚀性的影响。结果表明:3种成分的电弧熔炼态合金凝固组织主要由C15-Cr2(Nb,Ti)相和六方的β-(Ti,Nb)以及体心立方结构的β-(Nb,Ti)相组成。在5Ti和10Ti合金冷速较小的铸锭上部凝固组织中出现了亚稳相C14-Cr2(Nb,Ti)。通过对合金力学性能研究表明,随合金化元素Ti含量的增加,Laves相Cr2Nb合金的显微硬度逐渐降低,断裂韧性增大,当Ti含量达到15at%时,合金的断裂韧性达到了3.1 MPa·m1/2,比单相Laves相Cr2Nb提高1倍。另外,对腐蚀性能的测试表明,Ti含量增加材料腐蚀性能下降,但15Ti合金仍表现出良好的耐蚀性。     

Pressure sintering of W-15wt.%Cu alloys prepared by mechanical alloying as a subsequent densification treatment method

1. Introduction W-Cu alloys are widely used in many fields due to their superior properties [1]. With the rapid de-velopment of technology, more demands are being made on the W-Cu alloys. For instance, higher heat conductivity, lower thermal expansion coefficient, and more rigorous air tightness are required when these alloys are used for electronic package materi-als, such as heat sink materials. Especially, the re-quirement of more rigorous air tightness means that the W-Cu alloys must pos…