Method for fabricating dimensionally accurate pieces by laser sintering

A method for the fabrication of dimensionally accurate metal pieces by sintering a material which, before the sintering, consists of a blend of at least three pulverous ingredients, the first ingredient being an iron-group metal, the second ingredient being copper and phosphorus, and the third ingredient being an alloy of copper and at least one other metal, this powder blend of ingredients containing the third ingredient in the largest amount and both the first ingredient and the second ingredient in smaller amounts, characterized by the following combination:

• the shape of the piece is effected by layer-by-layer freeform selected area laser sintering, wherein a layer of the said powder blend is spread onto a base, those regions of the layer which correspond to this cross-sectional surface of the piece are heated to the sintering temperature by a laser beam, step by step, whereafter successive powder layers are spread one on top of another, in each of which those areas which correspond to the cross-sectional surface of the piece according to the layer concerned are laser sintered, and that
• the sintering is carried out in a gas atmosphere which contains a chemical compound, at least of an iron-group metal, which decomposes at the said sintering temperature, the iron-group metal depositing onto those areas of the cross-sectional surfaces of the piece which are being sintered at a given time.