Understanding and Predicting Ultra High Temperature Ceramics

A 3 year fully funded PhD studentship has become available at Imperial Collge London.

Supervisors: Prof. Mike Finnis and Prof. Bill Lee (Imperial College), Dr. Paul Bristowe (Univ. of Cambridge)

This project involves free energy calculations with DFT accuracy for predicting stability and thermophysical properties of new materials. It is available starting in October 2017, and is open to applicants from the European Economic Area.

Compounds of two or three of the elements  B, C, N, Al, Si, Ti , Zr and Hf include a number of remarkable ultra high-temperature ceramics that display metallic properties!  Of particular interest are the so-called MAX phases where letters M, A and X each stand for one element in an instance of the following general formula (Ti,Zr)n+1(Al,Si)(C)n where n=1 or 2 [1]. These materials have extraordinary damage resistance among other unusual properties, and are candidates for future use under extreme conditions of temperature and irradiation. For example there is an elusive MAX phase compound Zr2AlC, but experimental work at Imperial suggests it might only be stabilised by inclusion of impurities such as Si (replacing Al). Tools for calculating phase diagrams (e.g.ThermoCalc) lack essential information about the stability of these compounds. Theory and simulation can provide new knowledge, as we recently demonstrated with ZrC, by calculating the essential role of vacant carbon sites. We now have tools based on density functional theory (DFT) with which free energies can be calculated up to nearly the melting point [2] – or even above, and these will be applied to understand and predict properties, including the role of impurities and other point defects.

For more information and to apply please contact Professor Mike Finnis: m.finnis@imperial.ac.uk with a CV and transcripts.

Deadline for applications: 31 August 2017

[1] Barsoum MW, Radovic M. Elastic and Mechanical Properties of the MAX Phases. In: Clarke D.R., Fratzl P., editors. Annual Review of Materials Research, Vol 41, 2011. p.195.

[2] Duff AI, Davey T, Korbmacher D, Glensk A, Grabowski B, Neugebauer J, Finnis MW. Improved method of calculating ab initio high-temperature thermodynamic properties with application to ZrC. Phys. Rev. B 2015;91:214311.

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