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Grain Refining Performance of Al-B Master Alloys with DifferentMicrostructures on Al-7Si Alloy
Tongmin Wang,Zongning Chen,Hongwang Fu,Tingju Li 대한금속·재료학회 2013 METALS AND MATERIALS International Vol.19 No.2
The improved halide salt route has been employed to produce Al-3B master alloys with different microstructures. The microstructural features of AlB2 particles exhibited different impacts on the grain refining response of Al-7Si alloy, evolving with the holding time after inoculation. Large blocky AlB2 particles sufferfrom an intense fading effect while strip-like particles are not effective enough at the 0.005 wt% B addition level. Among the various Al-3B master alloys, sample 1 containing fine, blocky AlB2 particles was revealed to be the most efficient in refining Al-7Si alloy. With inoculation of only 0.005%B of such alloy, the final grainsize of Al-7Si alloy can reach 238 μm. Its grain refining efficiency was more or less retained for holding times up to 60 min.
Kateryna Svynarenko,Yubo Zhang,Jinchuan Jie,Valentyna Kutsova,Tingju Li 대한금속·재료학회 2017 METALS AND MATERIALS International Vol.23 No.4
When Al-Ti-C master alloys are produced via the conventional Self-propagating High-temperature Synthesis(SHS), the reduction of production temperature below 1523 K leads to the drastic deterioration of the refiner efficacy. In the present work, a simple yet effective way to improve the combustion process for low TiC-containingrefiners is proposed. The SHS reaction was performed to obtain Al-10TiC slurry first, which subsequently wasmixed with Al-Ti melt to obtain Al-5Ti-0.2C master alloy. By means of the proposed method, the process temperaturewas lowered to 1323 K. According to the results, in the case of improved SHS approach, the Al temperatureafter the onset of reaction increases by 90-100 K more than in the case of conventional preparation route,providing better kinetic conditions for TiC formation. As a result, at 1323 K production temperature, the averagecarbide size increases by 100% as compared to the conventionally produced refiner, which is claimed to be a reasonfor the improved refining performance of master alloy.
Characteristics of Copper-Clad Aluminum Rods Prepared by Horizontal Continuous Casting
Yubo Zhang,Ying Fu,Jinchuan Jie,Li Wu,Kateryna Svynarenko,Qingtao Guo,Tingju Li,Tongmin Wang 대한금속·재료학회 2017 METALS AND MATERIALS International Vol.23 No.6
An innovative horizontal continuous casting method was developed and successfully used to prepare copper-cladaluminum (CCA) rods with a diameter of 85 mm and a sheath thickness of 16 mm. The solidification structure andelement distribution near the interface of the CCA ingots were investigated by means of a scanning electron microscope,an energy dispersive spectrometer, and an electron probe X-ray microanalyzer. The results showed that theproposed process can lead to a good metallurgical bond between Cu and Al. The interface between Cu and Al wasa multilayered structure with a thickness of 200 μm, consisting of Cu9Al4, CuAl2, α-Al/CuAl2 eutectic, and α-Al +α-Al/CuAl2 eutectic layers from the Cu side to the Al side. The mean tensile-shear strength of the CCA sample was45 MPa, which fulfills the requirements for the further extrusion process. The bonding and diffusion mechanismsare also discussed in this paper.
Kateryna Svynarenko,Yubo Zhang,Jinchuan Jie,Valentyna Kutsova,Tingju Li 대한금속·재료학회 2017 METALS AND MATERIALS International Vol.23 No.5
Al-5Ti-0.2C, Al-0.8Ti-0.2C, Al-8Ti-2C, and Al-10Ti master alloys were prepared and used to investigate theinfluence of excess Ti on the growth of TiC particles and its ability to nucleate Al-grains. The results of a microstructureanalysis of TiC-containing alloys and refined CPAl were interrelated to the results of a refinement test. Itwas found that the presence of excess Ti is essential at the stage of master alloy preparation, as it facilitates thegrowth and uniform distribution of TiC within the structure. In Al-5Ti-0.2C alloy containing excess Ti, carbideparticles grow faster and to a higher extent (from 0.29 μm to 0.44 μm) compared to Al-0.8Ti-0.2C alloy producedwithout excess Ti (from 0.29 μm to 0.32 μm). The results support the “Ti-transition zone theory” as the mechanismof grain refinement by TiC-containing master alloys. The refinement performance of Al-5Ti-0.2C is superiorcompared to the one achieved by adding Al-8Ti-2C and Al-10Ti master alloys in corresponding concentrations. For the TiC particles to become favourable nucleating sites, they must undergo certain interaction with excess Ti atthe stage of master alloy preparation.
전자기 듀오캐스팅으로 제조한 Al-Mn/Al-Si 하이브리드 알루미늄합금의 미세조직과 인장 특성
박성진,김종호,박준표,장시영,Park, Sung-Jin,Li, Tingju,Kim, Chong-Ho,Park, Jun-Pyo,Chang, Si-Young 한국재료학회 2012 한국재료학회지 Vol.22 No.2
The microstructure and tensile properties of Al-Mn/Al-Si hybrid aluminum alloys prepared by electromagnetic duocasting were investigated. Only the Al-Mn alloy showed the typical cast microstructure of columnar and equiaxed crystals. The primary dendrites and eutectic structure were clearly observed in the Al-Si alloy. There existed a macro-interface of Al-Mn/Al-Si alloys in the hybrid aluminum alloys. The macro-interface was well bonded, and the growth of primary dendrites in Al-Si alloy occurred from the macro-interface. The Al-Mn/Al-Si hybrid aluminum alloys with a well-bonded macro-interface showed excellent tensile strength and 0.2% proof stress, both of which are comparable to those values for binary Al-Mn alloy, indicating that the strength is preferentially dominated by the deformation of the Al-Mn alloy side. However, the degree of elongation was between that of binary Al-Mn and Al-Si alloys. The Al-Mn/Al-Si hybrid aluminum alloys were fractured on the Al-Mn alloy side. This was considered to have resulted from the limited deformation in the Al-Mn alloy side, which led to relatively low elongation compared to the binary Al-Mn alloy.