Resubmitted proposal. High-entropy alloys (HEAs) are loosely defined as solid solution alloys that contain more than five principal elements in equal or near equal atomic percent (at.%). The concept of high entropy introduces a new path of developing advanced materials with unique properties. In-situ neutron diffraction techniques subjected to continuous tension are used to study lattice strain changes, elastic constants, and elastic moduli as a function of temperature in the single-phase CoCrFeMnNi HEA. However, no studies have explored the conventional creep behavior of HEAs. We propose to study the evolution of the average phase strains, (hkl) plane-specific lattice strains, interphase lattice misfit, and grain-orientation texture during creep deformation and tension tests of the single-phase Al0.3CoCrFeNi (FCC) and dual-phase Al0.3CoCrFeNi (FCC + B2) HEAs at high temperatures.