Inclusions and Segregations in the Selective Laser-Melted Alloys: A Review

Abstract

This paper aims to review some important microstructural defects arising in the alloys manufactured by selective laser melting (SLM) or laser powder bed fusion (LPBF). During the manufacturing process, various defects can occur in metals, which can negatively impact their mechanical properties and structural integrities. These defects include gas pores, lack of fusions, keyholes, melt pools, cracks, inclusions, and segregations. In this review, heterogeneities such as inclusion and segregation defects are discussed. Other types of defects have been comprehensively discussed in other reviews. Inclusions refer to foreign ceramic particles that are present within the metal, whereas segregations refer to the uneven distribution of alloying elements within the microstructure of the metal. The cause of appearance, effect of different parameters, and methods to reduce them in the final part are also reviewed. The effects of these defects on the integrity of the produced parts are discussed. Solutions for the elimination or minimization of these defects are also suggested. Post treatments and modifications of an alloy’s composition can also help to improve its material properties and reduce its defect concentration.