Melting of an alloy powder bed with constant heat flux for application in selective laser sintering (SLS) is analyzed in this paper. Since melting of an alloy occurs in a range of temperatures, instead of at a single melting point, there will be a mushy zone - containing partially melted powders - between the unmelted region and the completely melted region. The mushy zone can be further divided into two sub-regions: (1) a lower part with constant porosity (shrinkage takes place), and (2) an upper part with constant volume (no shrinkage). Temperature distributions in different regions and locations of melting interfaces are obtained using an integral approximation method. The results show that increasing initial porosity and temperature of the powder bed accelerate the melting process. The melting slows down with increasing thermal conductivity of the interstitial gas. (c) 2006 Elsevier Ltd. All rights reserved.