Papers by Keyword: Al

Abstract: Cermet includes the excellent properties of ceramic materials and the advantages of metal materials, so it is an important new engineering material. In this paper, Al₂O₃-Al cermet is prepared using different molding process via the powder metallurgy method to study the properties of Al₂O₃-Al cermet. The conclusion are shown the increasing density of Al₂O₃-Al cermet is not obvious with increasing the forming pressure of cermet body during the initial and late processing, but the increasing density is more obvious under the forming pressure for 20-30MPa. The density of cermet materials are increased with prolonging holding pressure time, the initial increase speed is faster, and the later growth rate becomes weaker. When the molding pressure is 30MPa, the holding time is 10min, the sintering temperature is 900°C, the holding time is 1h, the prepared Al₂O₃-Al cermet adding sintering aids has a coated microstructure, which indicates that the large number of particles is migrated on the grain boundary. The sample density is 2.26g/cm³, the density is highest, the distribution of Al₂O₃ and Al phase is the most uniform. The buried sintering method is more suitable for the preparation of Al₂O₃-Al cermet composites than the nudity sintering method.

Abstract: The high-temperature mechanical properties and microstructure of HK40 heat-resistant steel with different content of Al were investigated. The results from scanning electron microscope and transmission electron microscope showed that a large amount of spheroidal and dispersed γ′ phase were observed HK40 steel with 4.72wt.% and 7.10wt.% Al. The diameter of γ′ phase decreases from about 1.5μm to 50nm after solution treatment of 1200°C for 5h. The results of short term tensile test showed that tensile strength at 900°C decreased and the elongation was improved with increasing Al content. The oxides in the alloy with 4.72wt.% and 7.10wt.% Al were more uniform and finer than that in the alloy with and without 1.68wt.% Al.

Abstract: Inoculation is a treatment applied to the liquid base iron, to supply one or more elements, such as Al, Ba, Ca, Zr, Sr, Ce, La etc. with active roles in developing graphite nucleation sites. The efficiency of inoculants is directly dependent on the sulphur level: lower sulphur, lower inoculating power or unpredictable results. The objective of this paper is to examine the effects of a S and O containing inoculant enhancer [S,O,Al,Ca-FeSi alloy] to conventional Ca,Ba-FeSi alloy, in the mold treatment of electrically melted grey iron at 0.035%S, 0.002%Al, 0.0005%Zr, (%Mn) x (%S) < 0.02. The wedge test samples [W3 – ASTM A367] were used to evaluate the influence of the cooling rate and inoculation on the carbides formation. It was re-confirmed that for above mentioned critical chemistry conditions, this iron is sensitive to chill formation, despite the carbon equivalent level at 3.8%. Inoculation enhancement increased the effectiveness of the Ca,Ba-FeSi standard inoculant.

Abstract: The work analyses microstructures of ZnAl4Cu1, ZnAl27Cu2 and ZnAl40Cu2Si2 alloys in cast condition and after heat treatment in relation to microhardness HV_0.2 and purity of the alloys. As shown the microstructure of ZnAl4Cu1 alloy contained η phase and eutectoid, which consisted phases α + η. ZnAl27Cu2 alloy contained α phase, eutectoid and ε phase, and ZnAl40Cu2Si2 alloy had a similar composition, but moreover contained Si particles. Microhardness in the molten state in ZnAl4Cu1 alloy was HV_0.2 = 94, in ZnAl27Cu2 alloy it was HV_0.2 = 117, and in ZnAl40Cu2Si2 alloy it was HV_0.2 = 142_.

Abstract: The Ga penetration process along grain boundaries of Al-based alloys while they are in contact with Ga containing aqueous solution was studied. It was shown that exposure in the solution at room temperature leads to the liquid Ga penetration process, which started with 3 minutes delay. The penetration rate for Al-4.7 % Zn (13 μm/s) is two times less than penetration rate in pure Al. As for Al-Cu alloys it was shown that penetration process occurs only for the alloys with 1.6 % Cu and less, but for larger value of Cu concentration Ga did not penetrate in Al. Comparison of the effect with pure Ga spreading over the alloys surface showed that the absence of penetration connected with absence of wetting.

Abstract: The influence of Al content on microstructure and creep behavior of Ni₃Al-Base single crystal superalloy was investigated. Two Ni₃Al-Base single crystal alloys with different Al contents were prepared in a vacuum induction furnace by screw selection crystal method.Optical microscope (OM), differential scanning calorimetry (DSC),scanning electron microscope (SEM),energy dispersive spectrometer (EDS),and X-ray diffraction (XRD) were used to observe the microstructure of the alloys.The experimental results showed thatthe volume fraction, mean size of the eutectic phase γ-γ′, γ′before and after heat treatment display differences with the Al content. It has been found that the stress-rupture lives increased with theAl content.The reasons may be as follows.Firstly, as content of Al increases, the reinforcing phaseγ′increases, resulting in the improvement of the precipitation strengthening.And secondly, the increasing of Al content leadsthe decreasing lattice mismatch of γ/γ′ phase, which enhances the coherent strain field around theγ′ phase and the hence increase the strengthening effect to the alloy.

Abstract: Smelting slag from mineral process and blast furnace process to vanadium titanium magnetite is a kind of precious secondary resource in which TiO₂ content is higher than 20%. Taking titanium-bearing blast furnace slag in Panzhihua region as research object, this paper analyzes four factors that affect the leaching rate of Al and Fe. The four factors are reaction temperature, reaction time, acid concentration, and the ratio of acid and slag. The conclusion drawn from hydrochloric acid leaching experiment is the factor that causes greatest effect to leaching rate of Al and Fe is reaction temperature, then reaction time follows. Acid concentration and the ratio of acid and slag cause insignificant affect. Appropriate leaching condition is 5h reaction time, 5mol/L hydrochloric acid concentration, 90°C~100°C reaction temperature and 1.2 the ratio of acid and slag. Max leaching rate of Al and Fe is 78.5% and 65.8% respectively.

Abstract: The Cu/Al composites are of vital importance in industrial applications due to their numerous advantages. The influence of the bonding temperature on the microstructure and morphology of the Cu/Al couples, fabricated using diffusion bonding method, is investigated in this paper. The interfacial morphology and constituent phases at the Cu/Al interface are analyzed by means of scanning electron microscopy equipped with energy dispersive X-ray spectroscopy. The results indicate that microstructural characteristics are associated with various bonding temperatures due to the accelerated inter-diffusion of atoms at higher temperature. The intermetallic layer is thicker with increasing the bonding temperature.