高温镁合金的成分、组织设计与制备加工技术进展

介绍了提高镁合金高温性能的主要途径及目前研究较多的Mg-Al系、Mg-Zn系和Mg-RE系合金,同时分析了正在开始研究的含Y、Sc、Gd等稀土的新型耐热镁合金;同时分析了耐热合金中的耐热相,耐热合金的加工制备工艺进展。     

Internal oxidation thermodynamics and microstructures of Ag-Y alloy

The thermodynamic data of pure Ag and Y were calculated. The phase constitution, composition of micro-region and microstructures of Ag-Y alloy after internal oxidation were investigated by X-ray diffractometry(XRD), energy dispersion spectrometry(EDS) and scanning electron microscopy(SEM). The results show that the internal oxidation behavior of Ag-Y alloy is feasible from the view of thermodynamics. The upper limit of oxygen partial pressure of Ag-Y alloy oxidation is a function of temperature. Two phases (Ag and Y2O3) appear in Ag-Y alloy after the internal oxidation. The surface of Ag-Y alloy is convex because of the volume expansion of oxide in the alloy and the composition of the convex part is Ag. In Ag-Y2O3 sintered bulk Y2O3 particles are distributed inhomogeneously and conglomerated seriously, but they are dispersed uniformly in the Ag matrix after severe plastic deformation.     

Morphology, structure and formation mechanism of silicide coating by pack cementation process

The MoSi2 coating on C 103 niobium based alloy was prepared by pack cementation method. The formative mechanism, morphology and structure of coating were investigated. The silicide coating was formed by reactive diffusion obeying parabolic rule during pack cementation process. It is found that the composite structural coating is composed of three inferior layers as follows. The main layer is composed of MoSi2, the two phases＇ transitional layer consists of NbSi2 and a few NbsSi3 and the diffuse layer is composed of NbsSi3. The dense amorphous glass layer formed on the surface at high temperature oxidation circumstance can effectively prevent the diffusion of oxygen into coating.     

Mechanical alloying of Mo—Si—Fe powders

Mechanical milling behavior of Mo-Si-Fe powders was investigated u sing XRD, SEM and TEM techniques. The mixtures of elemental molybdenum (>99%), s ilicon (>99%) and iron (>98%) powders with a stoichiometry of Mo5-xFe xSi3 (x=0.5, 1, 2) were milled in a planetary mill for up to 195 h. For all three powder mixt ures, high-energy milling of 60h led to formation of the Mo(Fe, Si) supers aturated solid solution (Moss); and to a remarkable expansion of the solub ility of Fe, Si in molybdenum. The transformation of Moss to an amorphous phase was identified after longer time milling. In the milling process, the grain size of Mo (Fe, Si) decreased gradually and the internal stress increased linearly. After 40 h milling, the grain size was reduced to about 11 nm. SEM analysis of milled powders showed that the particle size increased initially with milling time. After 195 h milling, particles exhibited a spherical morphology and the particle size were reduced to about 100 nm.     

Mo在水溶液中的耐腐蚀性能

综述了Mo在不同溶液中的电化学行为、电池作用腐蚀 行为，并从技术的角度总结了它在各种碱性溶液、酸性溶液、无机盐溶液以及海水中的耐蚀性能.最后对研究工作进行了展望.     

紫钨生产的亚微米级钨粉和碳化钨粉的形貌

用紫钨可以生产出亚微米级的钨粉和碳化钨粉。通过不同的制样手段 ,使用透射电镜和扫描电镜研究了用紫钨生产的钨粉和碳化钨粉的形貌变化。发现钨和碳化钨粉形状复杂 ,多为树枝状或链状颗粒团形式 ,碳化钨粉中有较多的晶体缺陷。     

亚微米AlNp/Al复合材料的组织与性能研究

通过机械干混和湿混(添加分散剂)两种混合工艺,制备了20％AlNp／Al复合粉末,并通过冷等静压一热挤压制备了亚微米AlNp／Al复合材料。对比分析了两种混合工艺条件下亚微米AlN的分散情况,同时分析和测试了复合材料的显微组织与性能。     

Microstructure and mechanical properties of 8YSZ ceramics by liquid-phase sintering with CuO-TiO2 addition

The 8% (mass fraction) yttrium-partially-stabilized zirconia (8YSZ) ceramic was fabricated via liquid phase sintering at 1 200–1 400 °C by adding different mass ratios of CuO-16.7%TiO₂ (molar fraction) as sintering aid. Relative density, microstructure, Vickers hardness and bending strength as a function of sintering temperature and additive content were investigated. The experiment results show that liquid phase sintering at low temperature can be realized through adding CuO-16.7% TiO₂ to 8YSZ. The Vickers hardness and bending strength of samples with sintering aid are generally much higher than those of samples without sintering aid for all sintering temperatures, and increase with the increase of sintering temperature. When the addition content of CuO-16.7% TiO₂ is beyond 0.5%, the relative density, Vickers hardness and bending strength decrease with the increase of the mass ratio of sintering aid. Low additions of sintering aid are beneficial to aiding densification; high additions of sintering aid are detrimental to the sintered properties mainly due to greater amounts of pores generated by the volatilization of oxygen with the eutectic reaction between copper oxide and titanium dioxide. It is found that the fine grain size and high relative density are two main reasons of the high bending strength and Vickers hardness of the materials.     

超细碳化钨粉末粒度测试方法的研究

应用显微镜法(SEM、TEM)、激光粒度法、X射线线宽法、比表面积法对自制超细碳化钨粉末粒度进行测量,探讨了测量原理、颗粒形状等因素对粒径测试准确度的影响。通过对实验结果的分析,研究对比了几种超细微粒表征手段的优越性和局限性。     

AgZnO电接触材料内氧化热力学和动力学研究

研究了Ag_Zn合金内氧化的热力学和动力学问题。热力学计算结果表明:Ag_Zn合金内氧化在热力学上是可行的。采用氧化增重实验测出了Ag_Zn合金氧化动力学曲线,结果表明:Ag_Zn合金快速氧化增重温度区间为600~800℃,且随着温度的升高,Ag_Zn合金的氧化越充分。内氧化法制备的AgZnO材料组织呈连续的网状分布,ZnO颗粒弥散分布于Ag基体中,Ag和ZnO结合紧密。