Determination of slip systems and their relation to the high ductility and fracture toughness of the B2 DyCu intermetallic compound

Abstract

DyCu single crystals with CsCl-type B2 structure were tensile tested at room temperature. Slip trace analysis shows that the primary slip system in DyCu with a tensile axis orientation of 〈1 1 0〉 is {1 1 0}〈0 0 1〉 and the critical resolved shear stress for {1 1 0}〈0 0 1〉 slip is 18 MPa. Slip traces were also observed from a secondary slip system, {1 1 0}〈1 1 1〉, and this slip system appears to be a key contributor to the previously reported high ductility and high fracture toughness of polycrystalline DyCu. Transmission electron microscopy determinations of the Burgers vectors of dislocations in tensile tested specimens revealed 〈1 0 0〉 and 〈1 1 1〉 dislocations, with 〈1 0 0〉-type dislocations being more abundant. The implications of these findings for the understanding of the mechanical properties of DyCu and the large family of ductile rare earth B2 intermetallics are discussed.