A numerical approach to investigate the heating and the ignition of powder mixtures by radiant energy is presented. The ignition study is based on the possibility of separating the initiation transient from the propagation process, by operating in thermal explosion mode. Binary systems such as Ti-Al, Ni-Al and Ni-Ti, characterized by different compounds, were taken as case study for the experimental tests and the numerical simulations. Data concerning heating and ignition transients were estimated by best fitting the experimental results. The energy stored in the pellet up to the ignition temperature can be calculated. Radiant absorbance dependency on sample temperature at the laser wavelength was evaluated for each studied system.