Structural and elemental mapping analyses were applied to characterize the mesostructure in the bulk metallic glass-forming Zr60FexCu30−xAl10and Zr60+xFe5Cu25−xAl10alloys. It is found that the observed meso-/microstructure is adjustable by the addition of Fe and tunes the acoustic anelasticity of the samples, while the relaxation time derived from our ultrasound measurements inversely scales with the mechanical properties and ductility of the alloys. The measurements also give data for the thermal diffusivity and coefficient of thermal expansion. Together with mechanical compression tests the results are further discussed on the basis of the thermo-elastic effect and the related role of heat dissipation on the propagation of shear bands in metallic glasses during plastic deformation.