Experimental results previously published have shown that the radial heat affected zone (HAZ) for a 500 nm thick Al sample in the femtosecond case is less than 2 mu m [Appl. Phys. Lett. 80 (2002) 3886]. The spread of radial thermal effects for femtosecond pulses is calculated, by developing a two-dimensional version of the two temperature model (TTM). The case of an axi-symmetrical geometry is simulated by a finite element technique. A physical metallurgy approach is used to define and to estimate the radial HAZ width from the calculations. The evolution of the temperature as a function of time is studied, leading to a radial HAZ width of 220 nm for 500 nm thick Al samples. Similar calculations in the nanosecond regime are also performed and compared to the femtosecond case. (c) 2005 Elsevier B.V. All rights reserved.