Published online by Cambridge University Press: 26 February 2011
Twinning modes in topologically close-packed A-15 compounds are examined from a geometrical viewpoint. The crystallographically possible twinning modes with a shear less than a certain maximum are tabulated along with the percentage of shuffles involved for each of the modes. Based on some simple criteria, two of the most likely modes for deformation twinning are discussed in detail. The shuffle parameters usually employed to determine the percentage of lattice shuffles for a given mode have not been found to be useful in these structures because the primitive unit cell typically contains more than one formula unit. One has to examine the distribution of atoms in detail in order to determine the percentage of shuffles involved.