Micropillar compression deformation of single crystals of the intermetallic compound ζ-FeZn13

The deformation behavior of the zeta phase in the Fe-Zn system has been investigated by micropillar compression tests at room temperature with the use of single crystals with 13 different crystal orientations prepared by the focused ion beam method. Two different slip systems, {110}< 1 (1) over bar2) and (100)[001], are observed to operate. The critical resolved shear stresses (CRSS) value for {110}< 1 (1) over bar2) slip is more than three times smaller than that for (100)[001] slip. From the anisotropy in CRSS for these two slip systems, {110} < 1 (1) over bar2) slip is predicted to operate for most crystal orientations, except for a narrow orientation region around [(3) over bar 05] where (100)[001] slip operates. The CRSS for {110}< 1 (1) over bar2) slip shows an inverse power-law scaling against the specimen size with an exponent of -0.517. The bulk CRSS value for {110}< 1 (1) over bar2) slip is estimated to be 62-76 MPa by taking into account the specimen size effects of CRSS. The reasons why {110}< 1 (1) over bar2) slip with a rather long Burgers vector (0.7700 nm) is selected as the easiest slip system are discussed in terms of the nature of atomic bonding in the crystal structure, especially the rigid atomic bonding within an Fe-centered Zn-12 icosahedron (for slip plane selection), and the energetic barrier height along the slip direction and the resultant possible dissociation schemes (for slip direction selection). Some implications are made on how the deformability of the zeta phase can be improved in the textured coating layer in galvannealed steels based on the results obtained. (C) 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.