A method of fabricating a part by selectively melting powder, the method comprising the following steps: depositing a first layer (12) of a first powder (2) having a first element as its main element; depositing, on the first layer, a second layer (15) of a second powder (22) having a second element as its main element, which second element is different from the first element; and moving a first energy beam (11), e.g. a laser beam or an electron beam, over the second layer (15), the energy delivered by the first beam serving to initiate an exothermic reaction between the first element and the second element, the energy given off by the exothermic reaction acting to locally melt together the first and second layers (12, 15).