The present invention relates to a method for forming a three-dimensional article through successive fusion of parts of at least one layer of a powder bed provided on a work table. Said method comprising the steps of: providing at least a first and second powder tank, providing a first type of powder in said first powder tank having a first particle size distribution, providing a second type of powder in said second powder tank having a second particle size distribution, providing a first sub-layer of said first type of powder on said work table, providing a second sub-layer of said second type of powder on top of said first layer of said first type of powder, fusing said first and second sub-layers simultaneously with a high energy beam from a high energy beam source for forming a first cross section of said three-dimensional article.