IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Copper-based shape memory alloys (SMAs) are prone for grain growth during thermomechanical and betatising treatments. The grain growth of the alloy leads to intergranular cracking on quenching to form martensite in the alloy, which in turn leads to poor mechanical properties including corrosion resistance of the alloy. In the present work, grain refinement of a CuZnAl shape memory alloy was done by adding 0.2 to 0.4 wt.% of zirconium, titanium and boron as grain refiners. The effect of these additions on the microstructure and shape memory properties of the alloys were studied. The results show that the Zr and Ti additions reduce the grain size from 1.5 mm to 200 μm and 500 μm respectively. The Zr-added alloy shows good strain recovery and corrosion resistance compared with the alloy in the other conditions.

Department of Metallurgical and Materials Engineering

Department of Applied Mechanics

Proceedings of SPIE - The International Society for Optical Engineering

Metallurgical and shape memory characteristics of grain-refined Cu-Zn-Al shape memory alloys

The nuclear, aerospace, naval and missile industries place emphasis on materials with high structural integrity and reliable performance so as to meet certain stringent requirements in service. Strength is not the only criterion for selection. Properties such as fatigue resistance, impact toughness and fracture toughness. are equally important. Electroslag refining (ESR) has been used widely and successfully over the years for improving the fatigue resistance, creep resistance, impact strength and fracture toughness of steels and alloy steels. But application of ESR to aluminium alloys is only a recent endeavour. A highstrength aircraft aluminium alloy IS: 7670 was therefore chosen for studies on the fatigue strength and the impact and fracture toughness. The results indicate that the fatigue resistance is considerably improved after refining and that the impact strength and fracture toughness of the refined alloy are comparable with that of the unrefined alloy. © 1993 Canadian Institute of Mining and Metallurgy Pergamon Press Ltd.

Canadian Metallurgical Quarterly

A study of the fatigue, impact and fracture toughness characteristics of electroslag refined IS: 7670 alloy

The electroslag refining technique is one of the modern tools which is capable of imparting superior mechanical and chemical properties to metals and alloys. Refining usually results in the elimination of a number of casting or solidification defects, such as shrinkage porosity, gas porosity, pipe, micro- and macro segregation. Remelting also imparts a directional grain structure apart from refining the size of the inclusions, grains and precipitates. This technique has over the years been used widely and successfully to improve the mechanical and chemical properties of steels and alloy steels which are used in the nuclear, missile, aerospace and marine industries for certain critical applications. But the application of ESR to aluminum and its alloys is only recent. This paper investigates the response of an aluminum alloy (corresponding to the Indian Specification IS:7670) to ESR. Based on theoretical considerations and microstructural evidence it elucidates how ESR of aluminum alloys differs from that of ferrous alloys. The improvement achieved in mechanical properties of the alloy is correlated with the microstructure.

Scandinavian Journal of Metallurgy

Effect of electroslag refining on microstructure and mechanical properties of IS:7670 alloy

Electroslag refining (ESR) is a process already well established for ferrous materials. In view of its obvious potential for improving material behaviour for critical applications, an attempt has been made to study the possibility of using ESR for a selected aluminium alloy (corresponding to the Indian Specification IS:7670). This paper outlines the difficulties involved in applying ESR to aluminium alloys and highlights the need for careful selection of slag composition. The mode of solidification and features of the macrostructure of the material refined with a halide slag are then correlated with the slag characteristics.