Preferred orientation and its effect on bulk physical properties of polycrystalline materials

Averaging methods used to derive preferred orientation parameters of polycrystalline materials are examined with particular reference to those parameters suitable for predicting bulk physical properties from the properties of individual crystallites. Attempts to correlate experimental values of thermal expansion and irradiation growth coefficients of polycrystalline graphite and zirconium alloys with the commonly used preferred orientation f-parameter are reviewed. The physical basis behind the derivation of the f-parameter is examined in some detail and the consequent restrictions on its general applicability pointed out. (author)