Invited Research Lecture on Deformation and Cracking in Complex Systems
Date: 23 Aug 2013 - 23 Aug 2013
Venue: SIMTech Training Room 1, Tower Block, Level 3
The aim of this lecture is to discuss the modes of deformation in various complex systems. These include plasticity in complex metallic alloys, where deformation occurs by the movement of partial dislocations leaving trailing faults, and can, under certain circumstances give rise to an increase in the yield stress with increasing temperature, as well as new ways of determining the toughness in small-scale tests. Work has also been carried out looking at the deformation of MCrAIY materials, widely used in aerospace applications, at temperatures above 1000°C, as a means of holding abrasive particles to the tip of a turbine blade. It is shown that such materials are extremely weak at these temperatures. The possibilities of strengthening these materials are discussed and ways of developing suitable materials are suggested.
About the Speaker
Prof Clegg is an internationally renowned expert in ceramic materials and mechanical hard coatings, particularly for their use at high temperatures. He is the Editor-in-Chief of the Journal of Ceramic Processing Research, and his scientific achievements have won him several scientific awards including the Verulam Medal and Prize (1998) from Institute of Materials. He has a broad scientific base in materials research, with strong expertise in powder processing of ceramics, fibres and composites and metal composites. He pioneered the concept of layered ceramics as an easy way of making 'tough' ceramics, and developed quantitative analyses to describe the behaviour of these materials under both mechanical and thermal loading and was responsible for setting up collaborative research programmes that successfully built and tested components to demonstrate the dramatically improved thermal shock behaviour of these materials as well as porous interface structures that can deflect cracks even after very prolonged heating at temperatures as high as 1600 °C. He has initiated and led several collaborative projects between industry and universities on layered ceramics with the European Union Framework programme, leading to the building and successful testing of combustor liners for heat engines and refractory shroud rings.
More recently, his research work has focused on ceramic powder processing and nanocomposite hard coatings on problems associated with mechanical behavior including cracking, stress build-up and shape changes under various loading and how such behaviors lead to material failure, in particular the role of crystal structure in limiting the extent of dislocation motion. Deformation processes have been studied using nanoindentation and cross-sectional transmission electron microscopy enabled by the development of novel specimen preparation techniques such as micropillar compression fabricated by FIB and anylysed by nanoindentation as a means of studying plastic flow and have been the first to carry out such tests at elevated temperatures. His work is relevant to the activities of STG and FTG.
2.00pm Presentation by Professor William J Clegg
Who Should Attend
Senior Management and managers of local companies and SMEs.
Registration for this lecture is free of charge. Seats are available on first-come, first-served basis. To reserve a place, please register online.
For technical enquiries: Dr Zeng Xianting, Email: xzeng@SIMTech.a-star.edu.sg; Tel: 6793 8521
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