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Title: Microstructure modelling of coated single crystal Ni-based superalloys
Author: Di Martino, Irene
Awarding Body: Loughborough University
Current Institution: Loughborough University
Date of Award: 2004
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Market-driven requirements for better performance of gas-turbine engines are the main drive towards the development of more advanced Ni-based superalloy/coating systems. The durability of such coated components is a crucial issue faced by the power generation and the aircraft industries, because coating life mainly controls the refurbishment and replacement of many engine parts, such as blades. Coated systems undergo a number of microstructural changes as a result of thermal exposure, which need to be understood for the creation of accurate microstructure-based life-prediction models. This work was mainly concerned with the evolution of the microstructure in both the parent material and the coating as a function of temperature and time in a number of single crystal Ni-based superalloys, coated witlith an MCrAlY coating. The microstructural changes occurring at various time/temperature conditions were studied using thermodynamic equilibrium calculations, scarming electron microscopy and energy dispersive X-ray analysis. Significant microstructural changes were observed in all of thermally exposed coated superalloy systems investigated. The outer oxide thickness increased with increasing time and temperature of exposure, and gradually became enriched in Al and Cr as expected, but also in Y, Ti and Ta. Regions in the coating which were depleted in the β-NiAl phase also increased with increasing thermal exposure. The coating/substrate interdiffusion region also underwent important microstructural changes, which included significant Ύ́ rafting and the formation f Cr-rich phases.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available