Papers by Keyword: Casting

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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: Yan Feng Liang, Jing En Zhou, Sheng Quan Dong, Tong Yang
Abstract: Al-4.5 wt. % Cu matrix composites reinforced with in situ SiC particles were synthesized using direct reaction synthesis (DRS). The microstructure and tensile properties of the in situ composites were examined by optical microscopy (OM) and transmission electron microscopy (TEM). The results showed that the in situ SiC particles could be obtained through the appropriate control of the fabrication parameters. The heat released by the formation of TiC effectively promoted the formation of SiC. The size of the in situ SiC particles in the matrix was about 0.2 μm.
868
Authors: Matthias Reihle, Michael Hofmann, Uwe Wasmuth, Wolfram Volk, Hartmut Hoffmann, Winfried Petry
Abstract: Composite castings exhibit high residual stresses, mainly because of different thermal expansion of the used materials. Similar to the in-cast cylinder liners in a motor block, a composite specimen, consisting of a steel insert and an aluminum cast surrounding, was analyzed by neutron diffraction. The temperature- and time-dependent change of lattice spacing and thus the strain evolution was investigated by in-situ experiments directly after casting and during the cooling of the part. Different cooling conditions were investigated using two different molds, namely a sand and a permanent (steel) mold, optimized for in-situ neutron diffraction.
484
Authors: José M. Gallardo, Francicso Gomez Cuevas, Jesus Cintas, Juan M. Montes
Abstract: As the first step in the restoration process of a Renaissance bronze statue, a comprehensive study of the metallic product was carried out. This paper reports metallographic features and their possible relation to the casting process. Tensile properties are also discussed as they depend on porosity and lead content, what can be useful in the restoration process.
1014
Authors: Robert Ramakrishnan, Benjamin Griebel, Wolfram Volk, Daniel Günther, Johannes Günther
Abstract: The paper at hand introduces a 3D printing (3DP) process for additive manufacturing of inorganically bound sand moulds. The fundamental differences to 3DP with organic binders (which is state of the art) are explained and the quality relevant process parameters of the inorganic process are introduced. Since the inorganic binder system is thermally activated during the printing process the main focus lies on the heating procedure. The properties of printed specimens are measured by the quality features fluid migration and strength for which novel methods of moulding sand testing are used. Results show that the identified process parameters have a significant influence on specimen properties. The interaction of the attributes fluid migration and strength are also shown. By understanding the relationship between process parameters and quality features the properties of printed inorganic sand moulds can be tailored to fit casting specific requirements.
441
Authors: Athul Karuna Ratnakaran, Amirthalingam Srinivasan, Uma Thanu Subramonia Pillai, Bellampettu Chandrasekhar Pai
Abstract: In this study, two Mg-Zn-Gd alloys (Mg-5Zn-5Gd and Mg-5Zn-3Gd) are fabricated using high purity raw materials and by a clean melting process and subjected to immersion testing. The results indicate an increase in corrosion rate for increase in Gd content and the results are correlated using SEM, XRD and EDS analyses. It is seen that RE addition provides a protective oxide coating over the sample surface thereby assisting the corrosion resistance.
631
Authors: Muziwenhlanhla A. Masikane, Hilda K. Chikwanda, Iakovos Sigalas
Abstract: Over the past years, the blended elemental powder metallurgy (PM) approach has been identified as one of the most promising strategies to reduce the cost of titanium-based components. However, oxygen pick-up, inhomogeneity of the microstructure and chemical composition are sometimes reported for PM parts. This work compares properties of a blended elemental Ti-6Al-4V alloy obtained by sintering under argon gas atmosphere with those of a vacuum cast alloy. Argon was purified by passing it through a series of oxygen and moisture traps prior to being introduced into the sintering furnace. Casting was performed under vacuum (1 x 10-3 mbar). The starting material in both processes was the cold isostaticaly pressed blended elemental (BE) Ti-6Al-4V powder compact. The BE powder was prepared by mixing 60Al-40V master alloy powder with commercial Grade 4 titanium powder (0.377 wt.% O2). The sintered and cast alloys were compared on the basis of oxygen pick-up, density, microstructure, chemical composition and hardness to determine which method is better. Although the BE approach could not eliminate the common challenges associated with powder metallurgy processing of Ti alloys, oxygen pick-up and additional contamination was lower compared vacuum casting. Sintering at 1350°C for 1 h could not achieve full density compared to casting, but the microstructure appeared more homogeneous. Both sintered and cast Ti6Al4V alloys were harder than wrought Ti6Al4V due to a high concentration of interstitial oxygen. The sinterered and sintered plus HIPed Ti6Al4V alloys were softer than as-cast Ti6Al4V due to lower oxygen pick-up and incomplete densification. From the contamination and homogeneity perspective, the BE approach is an attractive technique for processing of Ti6Al4V alloy.
421
Authors: Xin Wang, Li Sheng Zhong, Na Na Zhao, Vladimir E. Ovcharenko, Yun Hua Xu
Abstract: Ceramic particles (such as VC, NbC, TiC, and WC), which exhibit high hardness and thermal stability, can be used for in situ fabrication of carbide-reinforced iron matrix composites with high macro-hardness and toughness. In this study, we describe a novel in situ process comprising infiltration casting and heat treatment to form carbide-reinforced iron matrix composites with hard ceramic particles. Our proposed approach was used to integrate different alloy wires, which can easily form carbides, into the metal matrix and cast a known amount of carbon, such as gray cast iron, ductile cast iron, or ordinary white cast iron, to form alloy-reinforced iron matrix composites. Thermal treatment of the resulting composites allowed the alloy elements of the wire to react with carbon in the matrix to form evenly distributed carbide particles. This approach can be applied to a wide range of materials with different morphologies for fabricating composites, machining tools, and wear-resistant components.
461
Authors: Musbah Mahfoud, Prasad Ayyagari
Abstract: The present paper describes a method for predicting the imminence (hereafter referred as ‘quality’) of the chemical composition of a recycled alloy to that of a standard alloy of aluminum recycled alloy made from aluminum scrap (used automotive components). The present method allows the chemical composition of a recycled alloy to be predicted. The method has been validated experimentally, and the results obtained showed that the composition of the recycled alloy was close to that of the predicted one. These findings indicate that the present method can be successfully used for any other recycled alloys to predict the alloy composition based on the in-coming scrap alloys. In this work, the chemical composition of a synthesized recycled alloy was compared to an ASTM standard alloy with the nearest composition. It was found that the two compositions were very comparable. A deviation factor has been defined in order to understand the quality of the recycled alloy obtained with reference to the ASTM alloy.
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