Valerie Randle

Company

University of Wales Swansea

Department

Materials Research Centre, School of Engineering

Summary keynote speaker resume

Valerie Randle is a professor and a Chartered Engineer in the Materials Research Centre, School of Engineering , University of Wales Swansea . She has held a Royal Society University Research Fellowship and was awarded the Institute of Materials Rosenhain medal in 1998 for her research work in electron backscatter diffraction and grain boundary engineering. In total she has some 250 scientific publications including 4 textbooks. The most well-known of these is ‘Microtexture Determination and its Applications', recently rewritten and published as a second edition. During 1999 she was Welsh Woman of the Year.

Title of the lecture

Materials Characterization by Electron Backscatter Diffraction

Summary of the spoken topic

A cornerstone in the study of both natural and technological materials is characterisation of microstructure. In the widest sense this topic encompasses, for all phases present, morphology, chemical composition and crystallography. Until the last part of the twentieth century these aspects of microstructural characterisation were measured separately, as dictated by available technology. A landmark advance for the materials community occurred with the genesis of ‘microtexture', which for the first time provided integration of crystallographic parameters and other aspects of the microstructure. A definition of microtexture is ‘a population of crystallographic orientations whose individual components are linked to their location within the microstructure.'

An estimated 95% of microtexture determination is by ‘electron backscatter diffraction' (EBSD) in a scanning electron microscope (SEM), with the remaining 5% contributed mainly by transmission electron microscopy (TEM) counterparts to EBSD. Essentially, a stationary beam of electrons is diffracted by atomic planes in the sampled volume of specimen. Analysis of the resulting diffraction pattern provides crystallographic information which can be related back to its position of origin. Evaluation (indexing) of EBSD diffraction patterns and output of data in a variety of formats is in most cases fully automated. The most exciting EBSD output is an ‘orientation map', which is a quantitative depiction of the microstructure in terms of its orientation constituents.

EBSD is now firmly established as the most comprehensive experimental tool for quantitative characterisation and analysis of microstructure, and is used extensively in both research and industry. For the first time a wealth of information on topics relating to, for example, orientation distribution (texture), processing history, microstructure evolution, interfaces and structure/property links is now routinely accessible. Microtexture analysis can in principle be applied to any crystalline material, subject to suitable specimen preparation.