熔渗-焊接法制备W/Cu功能梯度材料的研究

采用熔渗－焊接法经过工Ｗ骨架制备,渗Ｃｕ及热压焊接三个步骤制备出Ｗ／Ｃｕ功能梯度材料,并对Ｗ／Ｃｕ梯度过渡层的显微结构进行了观察,对Ｗ／Ｃｕ功能梯度材料的热震性进行了测试。     

热处理过程中Mg-2Nd-4Zn-1Zr合金微观组织的结构特征(英文)

对比研究了Mg-2Nd-4Zn-1Zr合金在铸态和热处理态下显微组织结构的演变。借助TEM、SEM和XRD等研究发现,合金中的第二相有几种不同的种类特征。在铸态下,合金中存在的共晶化合物是由Mg、Nd和Zn构成的两种不同类型的三元相:T相和W相。然而,经过热处理,随着时间和温度的变化,T相几乎完全溶解进入α-Mg基体中,但W相仍然大量剩余在基体中。此外,随着热处理时间的延长,沿晶界分布的第二相的形貌由连续分布的网状逐渐转变为球状。在热处理过程中,合金中W相是一种高热力学稳定相,其数量随着热处理的进行而逐渐减少,并最终粗化、稳定地存在于基体中。     

快速凝固Mg-6Zn-1Y-1Ce合金的TEM组织(英文)

利用单辊甩带技术制备快速凝固Mg-6Zn-1Y-1Ce薄带,并利用透射电子显微镜和能谱仪分析薄带组织。结果表明:薄带近辊面区域晶粒内部和晶界处分布着高密度颗粒,颗粒密度在中间区域和自由面区域有所降低;快速凝固合金主要由过饱和的--Mg固溶体、T相和W相组成,同时还存在少量的二十面体准晶相颗粒和Mg4Zn7相颗粒;其中T相为体心正交晶体结构,是由于体心正方结构的Mg12Ce相中部分Mg原子被Zn原子代替而形成的。     

Microstructure and Wear Resistance Evolution of HVOFSprayed WC-（W,Cr）2C-Ni Coating with Post Heat Treatment In Air Atmosphere

WC-(W,Cr)2C-Ni coating was prepared on 1Cr18Ni9Ti stainless steel and C-276 Ni-base Hastelloy by high velocity oxy-fuel(HVOF)spraying.The effect of post heat treatment in air atmosphere on the microstructure,phase composition,microhardness,fracture toughness,and wear resistance of HVOF-sprayed WC-(W,Cr)2C-Ni coating was investigated.The microstructure and phase composition of the coatings were analyzed by means of field emission scanning electron microscopy(FESEM)and X-ray diffraction(XRD).The microhardness and fracture toughness of the coatings were measured using a microhardness tester and a Vickers hardness tester.Moreover,dry friction and wear behavior of the coatings sliding against Si3N4 ball was investigated using an oscillating friction and wear tester;and the worn surfaces of the coatings were analyzed by means of scanning electron microscopy(SEM).It was found that heat treatment within 500-800°C resulted in crystallization of amorphous phase in as-sprayed coating,generating nanoscale new phases such as NiWO4,CrWO4 and Cr2WO6.Besides,heat treatment led to increase of the microhardness of as-sprayed coating,and the highest microhardness was obtained after heat treatment at 800°C.The fracture toughness and wear resistance of the as-sprayed coating increased with increasing heat treatment temperature up to 700°C but tended to decrease with further elevating temperature.In other words,the mechanical properties and wear resistance of the as-sprayed coatings were worsened owing to excessive growth of oxidation grains and depletion of ductile Ni binder after heat treatment above 700°C.Thus it was suggested that as-sprayed ceramic composite coating should be post heat treated in air at a moderate temperature of 700°C so as to achieve the optimized mechanical properties and wear resistance.     

NiW合金基带电化学抛光过程研究

采用硫酸溶液作为抛光液对轧制辅助双轴织构技术制备的Ni5W合金基带进行电化学抛光,在不同的抛光液浓度下获得了表面状态不同的基带。利用X射线光电子能谱(XPS)、X射线衍射(XRD)、扫描电镜(SEM)等手段研究了抛光过程中表面物质相成分及成因。结果表明:抛光液浓度较低时基带表面会形成过量的氧化物和H2WO4,造成表面选择性溶解过程紊乱,导致无法抛光。通过优化抛光液浓度可在基带表面获得适当厚度的固体层和粘液层,电流通过时可获得良好的抛光效果。     

Temperature,current density and cobalt concentration effects on electrodeposited anticorrosive cobalt-tungsten alloys using factorial experiment design and ANOVA techniques

ABSTRACT

Corrosion processes can compromise the durability of metallic materials. One way to minimise the effects of corrosion is to coat them with corrosion-resistant alloys. In this study, Co–W alloys were produced by electrodeposition and their anticorrosive performance was evaluated at different levels of current density, Co bath concentration and bath temperature, using factorial experiment design and ANOVA techniques. This evaluation consisted of measuring corrosion current and using electrochemical impedance spectroscopy. Adherent and corrosion resistant alloys were obtained at the lowest temperature of experimental design (25°C) and current density (10?mA?cm^?2) values. From the corrosion tests, X-ray Diffraction and Scanning Electron Microscopy analysis it was possible to conclude that the increase in the tungsten percentage in the composition of the alloy generated an increase in corrosion resistance. Although the alloys’ chemical composition has influence on the corrosion resistance, their physical aspect, such as the presence of cracks, are more significant for the resistance to corrosion.     

稀土镧、钇对蓝色氧化钨氢还原的影响

借助于ＳＥＭ、Ｘ射线衍射技术及ＩＰＰ粉末粒度仪等系统地研究了稀土镧、钇对蓝色氧化钨（ＢＯ）氢还原的影响。结果表明：稀土元素镧、钇在蓝色氧化钨的还原钨粉中以氧化物及钨酸盐形式存在；还原后所得的钨粉颗粒大多为规则形状的多面体；稀土镧、钇和铝相似，强烈地抑制ＢＯ氢还原钨粉颗粒的长大，而且钇的作用更为显著。     

三辊穿孔和轧管所产生的钢管壁厚极差和波浪形内螺纹

定量描述了实际生产过程中三辊斜轧穿孔所产生的钢管壁厚极差和波浪形内螺纹，初步探讨了三辊轧管机对钢管壁厚极差和波浪形内螺纹的影响。     

爆炸加载下钨合金的断裂特性SCIEI

用微量炸药接触爆炸的方法，研究了钨合金９３Ｗ─４Ｎｉ─３Ｆｅ在高加载率条件下的断裂特性，通过宏、微观观察，以及与静态断裂特性相比较，发现随着加载率的增加，钨─钨界面裂纹增加，致使钨合金的断口呈脆性状态。     

预处理工艺对W6Mo5Cr4V2高速钢组织与性能的影响

研究了预处理工艺对Ｗ６Ｍｏ５Ｃｒ４Ｖ２高速组织与性能的影响。试验结果表明，与退火预处理相比，调质预处理的奥氏体晶粒细小，未溶碳化物少，残留奥氏体量多，屈服强度高，低应力区疲劳寿命长，但抗弯强度，塑性，冲击韧度，断裂韧性都较低，高应力区疲劳寿命也短。