Vol.60, Nos. 2-3 - Indira Gandhi Centre for Atomic Research

More documents

Recommendations

Info

Trans. Indian Inst. Met. Vol.60, Nos. 2-3, April-June 2007, pp. 245-250 TP 2133 Effect of Alloying Elements on the Microstructural Evolution of Mg-Sn Based Cast Alloys D.H. Kang, S.S. Park 1 , In-Ho Jung 2 and Nack J. Kim Center for Advanced Aerospace Materials, Pohang University of Science and Technology, Pohang, Korea 1 Energy, Materials Research Center, Korea Institute of Machinery and Materials, Changwon 641-831, Korea 2 Magnesium Project Team, Research Institute of Industrial Science and Technology, Pohang, Korea E-mail: sunset@postech.ac.kr (Received 30 June 2006 ; in revised form 20 November 2006) ABSTRACT A study has been made on the effect of Sb and Sr on the microstructure and mechanical properties of Mg-Sn-Al-Si based (TAS) alloy. When Sb is added more than 3 wt.%, Mg 3 Sb 2 particles acted as nucleation sites for Mg 2 Si and Mg 2 Sn particles. Increased volume fraction and decreased shape factor of the particles improved the hardness of the alloys. When Sr is added, a few kinds of particles such as rod-like MgSi 2 Sr, SiSr 2 and polygonal Sr 5 Sn 3 particles are formed within the microstructure. Large volume fraction and uniform distribution of the particles greatly improved the hardness of the alloys. These microstructural changes by Sb, Sr addition are also expected to have beneficial effect on the room and high temperature mechanical properties. Trans. Indian Inst. Met. Vol.60, Nos. 2-3, April-June 2007, pp. 251-256 TP 2134 Non-Newtonian Behaviour of Liquid Metals V. Varsani and Z. Fan BCAST (Brunel Centre for Advanced Solidification Technology) Brunel University, Uxbridge, UK E-mail: mepgvhv@brunel.ac.uk (Received 30 June 2006 ; in revised form 20 November 2006) ABSTRACT Viscosity is the most structure-sensitive physical property of liquids, and is of great importance to diverse scientific and engineering disciplines. However, the shear rate dependence of the viscosity of liquid metals is so far not clear. A long-standing belief is that liquid metals are Newtonian liquids. Here we show for the first time that liquid metals are non-Newtonian liquids. We found that at temperatures close to their melting temperature, the viscosity of liquid metals increases linearly with increasing shear rate. The viscosity data obtained by extrapolation to zero shear rate are in good agreement with the literature values. Furthermore we found that the slope of viscosity against shear rate is proportional to the liquid density, the atomic diameter and the atomic packing density. We believe that this discovery will have a profound influence on research into the atomic structure of liquid metals, nucleation during solidification, and viscosity measurement. It will provide a dynamic approach to the research in such disciplines.
Trans. Indian Inst. Met. Vol.60, Nos. 2-3, April-June 2007, pp. 257-261 TP 2135 Role of Combined Addition of Sr and Sb on the Microstructure and Mechanical Properties of Cast A356 Alloy A.K. Prasada Rao, K. Das 1 , B.S. Murty 2 and M. Chakraborty 1 CAAM, Pohang University of Science and Technology, Pohang, Republic of KOREA 1 Department of Metallurgical and Materials Engineering, IIT Kharagpur, INDIA 2 Department of Metallurgical and Materials Engineering, IIT Madras, Chennai, INDIA E-mail: akprasada@yahoo.com (Received 30 June 2006 ; in revised form 20 November 2006) ABSTRACT Present paper describes the effect of melt inoculation of A356 alloy using Sb and Sr on its microstructural and subsequent influence on the mechanical properties of the same. The effect of melt holding time has also been investigated. The results show that Sr is better modifier for shorter holding time, and its modification efficiency is lost on longer holding of the melt. Interestingly, modification efficiency of Sb increases with the holding time. The results show encouraging behavior of these modifiers both at short as well as longer holding. The tensile and wear properties of A356 alloy modified using combined addition of Sr and Sb are promising. Trans. Indian Inst. Met. Vol.60, Nos. 2-3, April-June 2007, pp. 263-266 TP 2136 Pattern Formation During Slow Solidification Studied by means of a Phase-Field Method W. Miller 1* and I. Rasin 1,2 1 Institute for Crystal Growth, Berlin, Germany 2 Technion, Haifa, Israel E-Mail: miller@ikz-berlin.de (Received 30 June 2006 ; in revised form 20 November 2006 ) ABSTRACT An extended phase-field method has been used to compute the cellular structures in the range of 10th of m up to some mm, which occur during a slow growth process of Ge x Si 1-x single crystals. Trans. Indian Inst. Met. Vol.60, Nos. 2-3, April-June 2007, pp. 267-271 TP 2137 Methodology to Characterize Microsegregation A. Hazotte and J. Lacaze 1 LETAM, UMR CNRS 7078, Univ. Paul-Verlaine, Ile du Saulcy, Metz cedex 01, France 1 CIRIMAT, UMR CNRS 5085, ENSIACET, 31077 Toulouse cedex 4, France E-mail : Jacques.Lacaze@ensiacet.fr (Received 30 June 2006 ; in revised form 20 November 2006 ) ABSTRACT Chemical microsegregation resulting from solidification of metallic alloys is most often characterised by EDS or WDS microanalysis using spot measurements located along a regular grid. Due to experimental limitations, the wave lengths of both dendrite arms and analysis grid are often of the same order of magnitude. Although this fact is generally eluded, it complicates the statistical analysis of the results, in particular when the objective is to validate a given solidification model or to prove the occurrence of solid state diffusion. This is first illustrated in the present work by means of experimental analysis performed on an Al alloy. The problem is then tackled using 2D simulations of more or less periodic solidification structures which are sub-sampled along periodic or random point distributions of different surface densities. Statistics tools are used to compare the resulting chemical distributions with the solidification model (Gulliver-Scheil model) injected in the simulation. This allows pointing out the limitations of classical statistical approach in that case, and finally to propose an optimum –at least less bad- procedure to characterise microsegregated structures.
Page 1 and 2: Trans. Indian Inst. Met. Vol.60, No
Page 15: Trans. Indian Inst. Met. Vol.60, No
Page 25: Trans. Indian Inst. Met. Vol.60, No

Vol.60, Nos. 2-3 - Indira Gandhi Centre for Atomic Research

Create successful ePaper yourself

Delete template?

Save as template?