The exceptional high temperature mechanical properties of Ni-base superalloys has resulted in their widespread use in high temperature applications. These alloys conventionally derive their properties from the presence of coherent Ni3Al or Ni3Nb precipitates within a nickel matrix. Recent studies have, however, identified the potential of a new class of Ni-base superalloys strengthening by Ni3V precipitates, with higher temperature stability than those based on Ni3Nb. The properties of these alloys are strongly influenced by the lattice misfit between the matrix and precipitates. It is therefore important that the response of the lattice parameter to alloying is understood. Given the crystal structure of the phases present in these alloys and their site occupancies, neutron diffraction is the ideal tool to accomplish this and as such a request is made for 2 days of beam time on Polaris.