Papers by Keyword: Master Alloy

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Authors: Sundaram Kumar, Sam Agarwal, Keyna O'Reilly
Abstract: Master alloys are used in the metals industry to control chemical composition and to help to achieve a particular microstructure or promote growth of desired phases. This study reports on making a Al3Nb containing aluminium (Al) - niobium (Nb) master alloy by solid-liquid reaction processing, where solid Nb particles are added to the liquid Al. Nb react with Al to form in-situ Al3Nb. The in-situ formed Al3Nb particles were facet and polygonal in shape. The three dimensional analysis revealed that the outer surface of the partially reacted Nb was covered with faceted Al3Nb particles. The different nature and morphologies of the in-situ phases that were produced were determined using SEM, EDX, XRD and extraction techniques. A mechanism for the observed microstructural difference is discussed.
515
Authors: Sundaram Kumar, Sam Agarwal, Keyna O'Reilly
Abstract: Master alloys are used in the metals industry to control chemical composition and to help to achieve a particular microstructure or promote growth of desired phases. This study reports on making a Al3Nb containing aluminium (Al) - niobium (Nb) master alloy by solid-liquid reaction processing, where solid Nb particles are added to the liquid Al. Nb react with Al to form in-situ Al3Nb. The in-situ formed Al3Nb particles were facet and polygonal in shape. The three dimensional analysis revealed that the outer surface of the partially reacted Nb was covered with faceted Al3Nb particles. The different nature and morphologies of the in-situ phases that were produced were determined using SEM, EDX, XRD and extraction techniques. A mechanism for the observed microstructural difference is discussed.
131
Authors: Da Li Cao, Ji Kun Wang, Si Chen Guo, Qin Hong Fang, Zhong Ning Shi
Abstract: The electrochemical formation of Al-Mg master alloys were investigated in NaCl-MgF2-MgO melt at 850°C. The results revealed that cell voltage was nearly constant during electrolysis process, Mg content in Al-Mg master alloys increased with increasing of electrolysis time when Mg content was less 7.03mass%, Mg content in Al-Mg master alloys can be up to 7.03mass% for 4h electrolysis. The results of XRD indicated that phase structure of the Al-7.03Mg mass% alloy existed single phase α-Al, MgCl2 and NaMgF3 in electrolyte were observed after electrolysis. And the formation mechanism of Al-Mg master alloy was discussed as well.
260
Authors: Viktória Rontó, Anna Sycheva, Jenő Sólyom, Péter Pekker, Ildikó Cora, Éva Fazakas
Abstract: Ti60(NixCu40-x)40 x = 5 - 40 at% ternary alloys were prepared by arc-melting followed by a centrifugal casting into a wedge-shaped copper mould in order to examine glass forming of these compositions. Microstructure of the master alloys and wedge-shaped samples were studied. Among the master alloys, which solidified under non-equilibrium conditions, the sample with 15 at% Ni content displayed clear eutectic structure and its wedge-shaped sample had the finest structure but still crystalline. Microstructure of the other compositions was far from amorphous state.
491
Authors: C. Tojal, T. Gómez-Acebo, F. Castro
Abstract: The use of boron for successfully obtaining high density PM stainless steels with improved mechanical properties and corrosion resistance is presented. Boron is added as part of master alloys which have been specifically designed to provide the formation of wetting liquid phases with excellent characteristics for producing controlled densification and alloying of 316L and 304L austenitic stainless steels. The as-sintered density and properties of these alloys is determined by the amount of master alloy, the chemical composition of the stainless steel powder, the sintering temperature and time. The microstructural development and alloy homogenisation are determined by the chemical composition of the Fe-based powder and the chemical reactions taking place between the basic powder and the master alloy particles during high temperature sintering. The use of this master alloy is shown to lead to stainless steels with outstanding combinations of strength and ductility. The influence of alloying and the sintering conditions on the final microstructure, density, corrosion resistance and tensile properties is also discussed.
661
Authors: Orest M. Ivasishin, Daniel Eylon, V.I. Bondarchuk, Dmytro G. Savvakin
Abstract: In the present study titanium alloys were synthesized by the blended elemental press-andsinter powder metallurgy approach using hydrogenated titanium powder. Experimental investigation and modeling of the homogenization processes during synthesis were used to analyze peculiarities of mass transfer and factors affecting diffusion. Processes of alloying elements redistribution during chemical homogenization of powder blends are shown to be strongly dependent on the chemical composition of the initial powders. Optimization of the processing parameters allows to synthesize uniform, nearly-dense material with reduced grain size, at relatively low temperatures and short time. This will provide improvement of mechanical properties simultaneously with better cost-effectiveness of the process.
177
Authors: Jin Shan Zhang, Yong Jun Xue, You Jun Guo, Chun Xiang Xu, Wei Liang
Abstract: Effect of Si on the forming ability of quasicrystalline phase in Al65Cu20Fe15 alloys fabricated under conventional casting conditions has been studied using X-ray diffraction (XRD), optical microscopy (OM), and scanning electron microscopy (SEM). The results show that under the conventional casting conditions, it is found that the addition of certain amount of Si into the Al-Cu-Fe melts can change the formation of Al62.5Cu25Fe12.5 quasicrystals during the solidification process. Compared with Al65Cu20Fe15 alloy, Al64.5Cu20Fe15Si0.5 alloy has smaller volume fraction of β phase solidifying initially, larger volume fraction of the quasicrystal phase generating in the subsequent peritectic reaction, and larger volume fraction of ω phase solidifying finally. Both experimental results and the theory of Hume-Rothery show that addition of Si can promote the formation ability of the icosahedral quasicrystalline Al62.5Cu25Fe12.5 phase in Al-Cu-Fe alloy.
619
Authors: Yong Feng Wang, Rui Li
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.
291
Authors: Jing Cao, Yong Feng Wang, Chun Xue Wei
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.
887
Authors: José M. Torralba, Raquel De Oro, Mónica Campos
Abstract: Since low alloyed sintered steels were introduced in the market of the structural parts, we have followed the evolution of a material with poor mechanical properties and any uniformity (in the sense of reproducibility) to materials that today are produced with high reliability and performance. The working efficiency could be equivalent in many cases with the best wrought steel, and maintaining a good margin in terms of cost and competitively. In this paper a complete review of the topic is accomplished, from the early times when the first parts were made by plain iron or iron-carbon, going through the different alloying systems: Fe-Cu, Fe-P, Fe-Cu-Ni-Mo, and more recently Fe-Cr-Mo and Fe-Mn. The development in processing routes has been considered too. The main milestones in the field of new alloying systems have been: 1) the introduction of Cu in 60-70’s, 2) the new complex systems with Cu-Ni-Mo in the 80’s and 3) the introduction of alloying elements with high oxygen affinity (in the late 90’s). Regarding the milestones in processing could be considered: 1) the development of new mixing procedures, 2) the warm compaction and high velocity compaction, 3) the improvements in sintering control and high temperature sintering. Several decades of research and innovation, acting on the processing system (mixing, pressing, sintering, post-sintering operations,…) and on the alloying system (from the earliest times with plain iron to complex systems used today), has allowed us to have a highly competitive materials, in terms of performance, and processes in terms of cost. The future is still open to new developments.
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