The Harold Hyam Wingate Foundation
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Doctor Bruce Burton

Nationality: United Kingdom

Year: 2003

Subject Area: Science and Engineering

The scholarship enabled me to pursue theoretical work on novel aspects of the high temperature deformation of polycrystalline materials. Under stress, individual crystals (or grains) in the polycrystalline structure undergo i) changes in shape, ii) relative sliding between grains along grain boundaries and iii) grain rotation about the common boundaries between grains. The theory of the former two processes is well-developed, but there is little theoretical understanding of grain rotation. This was the justification for the awarded Scholarship. During the duration of the Scholarship, theoretical studies on grain rotation resulted in the following publications:

(1) Theory of boundary diffusion controlled grain rotation in a ‘bamboo’ structure
B BURTON Materials Science and Engineering (2004) 20 1215.

(2) Grain rotation resulting from cavity sintering B BURTON Materials Science and Engineering (2004) 20 1513.

(3) Theory of diffusional rotation about the common boundary of a bicrystal
B BURTON Philosophical Magazine (2005) 85 1901.

(4) Theory of bending of polycrystalline beams by creep at low stress B BURTON to be published in Philosophical Magazine (2007).

A novel and unexpected outcome of the work covered in the last publication showed that individual grain volume need not be conserved during the diffusional deformation of polycrystals. The assumption of grain volume conservation has been implicit in all theories of the diffusional creep of polycrystalline matter that have been published over the last half century. As a consequence of the present work, not only has the theory of grain rotation been elucidated for the first time, but the prospect of incorporating volume non-conservation aspects in a wide range of diffusion-controlled phenomena has been revealed. This includes, creep, creep fracture by cavity growth, cavity sintering and super-plasticity. The way forward has been clearly defined and several publications on grain rotation are in draft form and one on the role of the non-conservation of grain volume has been accepted for publication (Non-conservation of grain volume during diffusion creep B BURTON to be published in Materials Science and Engineering).