In defense of diffusional creep

Over the last decade, Ruano and coworkers have presented a series of papers in which they attempted to negate the evidence for diffusional creep as a deformation mechanism. In the present paper it is argued that, since diffusional creep theory is based on sound physical principles, it is more fruitful to investigate areas in which the theory needs modification to account for experimental departures from it, rather than to reject it entirely. Some of these modifications are discussed. Specific replies to several of the criticisms are given, involving some analysis and some additional metallographic evidence. Results on the influence of stress on thermal grooving during low stress creep are presented as unique evidence of a diffusional mechanism of deformation.