Papers by Keyword: Al₃Ti

Abstract: The effect of the high-energy synthesis of Al-Ti composite powders in a planetary mill on the as milled and heat treated structures was investigated with XRD and SEM. The results indicate that with the increase of milling time, the intensities of diffraction peaks corresponding to Al and Ti decrease and broaden gradually and the amount of low intensity lines decreases continuously. There is no new intermetallic compound in the Al-Ti mixed powders even after milling 200 h. The increase of rotation speed has significant influences on the Al-Ti composite powders, and milling 50h with rotation speed of 400 rpm has a same effectiveness with milling 200 h with rotation speed of 300 rpm. The diffraction peaks of Al and Ti both disappear in the Al-Ti composite powders milling 50h with a rotation speed of 300 rpm after thermally insulated at 610°C for 2h, indicating the formation of Al₃Ti tetragonal phases. The higher the milling energy, the lower the reaction temperature of Al₃Ti formation is.

Abstract: Formation mechanism of TiC in Al matrix at a rather low melting temperature using in situ technology was studied. And effect of the melting temperature on the microstructure of in-situ TiC/Al composite was investigated. The results indicate that, the resultants of TiC and Al₃Ti were found out in the matrix; however, no evidence showed that Al₄C₃, a resultant phase existed probably in TiC/Al composite in accordance with the relative reference, was found out. Compared to the sample of T750, more TiC and less Al₃Ti existed in the sample of T850, and morphography of Al₃Ti changed from block to bar with the increasing melting temperature. The melting temperature affected extremely the reaction speed and the resultants.

Abstract: Ti-(Al₃Ti+Al) and Ti-Al₃Ti laminated composites have been fabricated in vacuum using 50, 100, 150, 200, 400 and 600 μm thick titanium and 50 μm thick aluminum foils. The composites were synthesized with controlled temperature and treating time. Microstructural examinations showed that Al₃Ti was the only phase formed during the reaction between Ti and Al. The initial foil thicknesses only affected the volume fraction of the resultant Ti, Al and Al₃Ti layers. Treating time at 650 °C was a main factor determining microstructures and properties of the composites. After 20 minutes not all aluminum was consumed and therefore the composites consisted of alternating layers of Ti, Al and Al₃Ti. After 60 minutes aluminum layers were completely consumed resulting in microstructures with Ti residual layers alternating with the Al₃Ti layers. Mechanical tests were performed on the materials with different microstructures to establish their properties and fracture behavior. The results of investigations indicated that mechanical properties of the composites strongly depended on the thickness of individual Ti layers and the presence of residual Al layers at the intermetallic centerlines.

Abstract: Al3Ti-based intermetallic compound coatings were formed on AA6063 aluminum alloy by laser cladding. The microstructure, wear and corrosion behaviors were investigated. The results showed that, the laser cladding coatings were made up of Al3Ti dendrites, interdendritic α-Al and uniform distribution of TiC particles, and showed good bonding to the substrate. The microhardness, wear and corrosion resistances of the laser cladding coatings greatly increased compared to the substrate. And with the addition of TiC particles to the coating, the superficial properties are improved simultaneously.

Abstract: Metal matrix composite comprising a multiphase magnesium matrix and titanium particles fabricated by hot pressing was characterized. Powder mixture of the Mg:Ti:Al at weight ratio equal to 10.5:6.1:3.4 was sintered at 640, 650 and 660°C whereas other parameters were held constant. Thermal effects during heating and cooling of powder mixture were measured by differential scanning calorimetry (DSC). Microstructure of composite was characterized by scanning electron microscopy (SEM) with a use of X-ray energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). For all conditions of components consolidation α-Mg, α-Ti, Mg₁₇Al₁₂ and Al₃Ti were identified. It was revealed that dispersion and location of Mg₁₇Al₁₂ and Al₃Ti compounds depended on sintering temperature. Measurements of hardness and density of obtained non-porous composite gave approximate results of 130 HV and 2.7 g/cm³ respectively

Abstract: AlTiC master alloys have been prepared by Contact Reaction Method（CRM）.X-ray diffraction，SEM and EDS were used to analyse the AlTiC master alloys. It showed that morphology and distribution of TiC and Al3Ti particle have correspondingly changed with the transformation of temperature. As a result, the change in morphology and distribution of TiC and Al3Ti particle has considerably affected the gain refining performance of AlTiC master alloys. The result showed that it had excellent grain refining performance for commercially pure aluminum in 800°C.

Abstract: AlTiC master alloys have been prepared by Contact Reaction Method（CRM）.X-ray diffraction，SEM and EDS were used to analyses the AlTiC master alloys. It showed that morphology and distribution of TiC and Al3Ti particle have correspondingly changed with the change of the size of powder. As a result, the change in morphology and distribution of TiC and Al3Ti particle has considerably affected the gain refining performance of AlTiC master alloys. The result showed that: when the grain size of Ti is much smaller, the effect of refinement is much better.

Abstract: Al-Ti alloys, which have Al3Ti platelet particles in Al matrix, were deformed by ECAP with routes A and Bc. With increasing the number of ECAP passes, Al3Ti platelet particles are fragmented and their sizes decrease. The microstructure of ECAPed Al-Ti alloy specimens by route A has a strong alignment of the fragmented Al3Ti particles. On the other hand, ECAPed Al-Ti alloy specimens by route Bc have a relatively homogeneous distribution of Al3Ti particles comparing with the specimen deformed by route A. Based on these results, it was found that ECAPed Al-Ti alloy specimen by route A has highly anisotropic microstructure. However, both ECAPed specimens with routes A and Bc have no anisotropic wear property. That is because the wear property of the Al-Ti alloy specimen depends on the shape of the Al3Ti particle. From these results, it was found that SPD induced by ECAP is an effective processing method to make homogeneous wear property for the metallic material containing platelet solid-particles.

Abstract: Microstructure and texture evolution during equal channel angular pressing (ECAP) of Al-5 mass%Ti alloy are investigated for up to 8 passes via routes A and BC. Platelet-shaped Al3Ti particles in the Al-5mass%Ti alloy are cracked severely with repetitive ECAP passes, and the mean size of the Al3Ti particles is decreased with increasing the number of ECAP passes. Microstructural observation showed that an Al–Ti supersaturated solid solution is formed during the ECAP process. It is also found that the Al-Ti alloy after ECAP by route A and route Bc methods have very different microstructures. Namely, after ECAP by route Bc, the fine Al3Ti particles are homogeneously dispersed in Al matrix, while the microstructure has highly anisotropic distribution after ECAP by route A.

Abstract: Three types of L12-type Al3Ti-Cr alloys, of compositions 67Al-25Ti-8Cr, 66Al-24Ti- 10Cr, and 59Al-26Ti-15Cr in atomic percent, were corrosion tested at 900, 1000, and 1100oC in an Ar-1% SO2 gas atmosphere for up to 150 h. The alloys were resistant to corrosion because a thin Al2O3 barrier layer was formed on the alloy surface due to the high Al content in the alloys. Due to the very strong Al affinity for oxygen, virtually no sulfur was detected inside the oxide scale.