Simulations of the positron response to the mechanical deformation of Ni3Al nanowires are performed on modelled samples obtained using molecular dynamics. Particular attention is paid to the evolution of the various open volume defects and their interaction during deformation. Positron simulations are done in conjunction with a general, geometrical analysis of open volumes in the studied samples, which brings complementary information to the positron response results. (C) 2008 Elsevier B.V. All rights reserved.