Copper films deposited on m- and r-plane sapphire substrates have been dewetted in either the solid or the liquid state, and equilibrated at 1253 K. The orientation relationships (ORs) between the dewetted copper crystals and the sapphire substrates have been investigated by electron backscatter diffraction. In addition, the shape of the copper/sapphire interface has been studied by scanning electron microscopy. Although the as deposited films develop {1 1 1} surfaces parallel to both substrates, after solid state dewetting the copper crystals on the m-plane substrate are found to change their interface plane from Cu{1 1 1} parallel to Al2O3 (m-plane) to Cu{1 1 1} parallel to Al2O3 (a-plane), and after liquid state dowelling the preferred OR of copper on both m- and r-plane substrates may be expressed as: Cu{1 1 1}< 1 1 0 > parallel to Al2O3 {1 1 (2) over bar 0} < 0 0 0 1 >. This OR is identical to that previously observed for copper on the sapphire a-plane. (C) 2015 Elsevier B.V. All rights reserved.