The spin-wave dynamics in partially ordered Fe75Pt25 and disordered Fe65Ni35 invar alloys are investigated in the subcritical and intermediate temperature ranges using the inclined geometry method (IGM) in small angle polarised neutron scattering (SAPNS). This method is based on the analysis of the left-right asymmetry in the magnetic inelastic SAPNS arising when the direction of the magnetisation in the sample is inclined to the incident neutron wave vector. The spin-wave (SW) parameters, such as the SW stiffness D and the SW damping Γ, are obtained by comparison of the antisymmetrical contribution to the scattering with a model function. The temperature behaviour of the SW stiffness D was fitted using expression: D~|τ|x, where τ=1-T/TC. It was found that x=0.48+/-0.01 and x=0.58+/-0.05 for the range |τ|>0.1 for FeNi and FePt systems, respectively. The temperature behaviour of SW parameters D and Γ breaks down near TC in the range |τ|<0.1. Hence, we observe a crossover from mean-field theory predicting x=0.5 to critical dynamics.