The universally used approximation for the magnetostriction constant o
f a polycrystalline material is based on the assumption of uniform str
ess through the aggregate. In this article we calculate the alternativ
e approximation of uniform strain. The calculation is performed in ter
ms of the grains orientation distribution (texture) function, and sing
le crystal constants describing the elastic and magnetostrictive aniso
tropy. These bounds represent the optimum solution of the incompletely
specified problem of crystallites shape distribution in a polycrystal
line aggregate. The available experimental data are compared with the
two approximations. (C) 1997 American Institute of Physics.