Journal of Materials Processing Technology 214 (2014) 1852–1860 Contents lists available at ScienceDirect Journal of Materials Processing Technology jo ur nal home p ag e: www.elsevier.com/locate/jmatprotec Selective laser melting of a beta-solidifying TNM-B1 titanium aluminide alloy Lukas Löber a,∗ , Frank Peter Schimansky b , Uta Kühn a , Florian Pyczak b , Jürgen Eckert a a Leibniz Institute for Solid State and Materials Research Dresden, Germany b Helmholtz-Zentrum Geesthacht Centre for Materials and Coastal Research, Germany a r t i c l e i n f o Article history: Received 18 November 2013 Received in revised form 28 February 2014 Accepted 2 April 2014 Available online 13 April 2014 Keywords: Additive manufacturing Selective laser melting Titanium aluminide Mechanical properties Optimization of process parameters a b s t r a c t The interest for a wider range of useable materials for the technology of selective laser melting is growing. In this work we describe a new way to optimize the process parameters for selective laser melting of a beta solidifying titanium aluminide. This kind of material has so far not been processed successfully by this method. The new approach is easy to conduct and well transferable to other materials. It is based on the fact that the parts generated from selective laser melting can be described by an addition of multiple single tracks. Multiple types of single track experiments are performed and in combination with knowledge from laser welding tests optimized parameter combinations are derived. Compact samples are built with the optimized process parameters and characterized in terms of microstructure, phase composition and mechanical properties. With this technique the generation of a TNMB1 titanium aluminide alloy sample with a density greater than 99% could be achieved. The mechanical properties are comparable with material produced by conventional techniques. © 2014 Elsevier B.V. All rights reserved. 1. Introduction Selective laser melting (SLM) is an additive manufacturing tech- nology which works layer wise and was developed from selective laser sintering. With the availability of new higher powered lasers it is now possible to fully melt the material according to Bourell et al. (1992). In SLM a laser source selectively scans a powder bed according to the CAD-data (Computer Aided Design) of the part to be produced. This three-dimensional CAD model of the desired part is always the starting point for this processing technique. It has to be divided numerically in horizontal layers of a defined thickness. In addition to the geometry, each layer contains also spe- cific information regarding the process parameters such as laser power, scanning speed or hatching. To fix the part on the substrate material, and to enhance heat conduction during SLM processing according to Hussein et al. (2013a), support structures have to be designed. Both the CAD model and the support structure have to be sliced as described by Löber et al. (2011). These filigree support structures are built up from the same material and in the same SLM process as the desired part and have to be removed mechanically afterwards as proposed by Hussein et al. (2013b). The complete ∗ Corresponding author. Tel.: +49 3514659503; fax: +49 3514659452. E-mail address: l.loeber@ifw-dresden.de (L. Löber). SLM process is a number of iterations of the same procedure which consists in applying powder, melting the selected areas of the pow- der bed with the laser and lowering the building platform to enable the next application of a new powder layer as described by Löber et al. (2013). A schematic of the process is shown in Fig. 1. The high intensity laser beam makes it possible to completely melt and fuse the metal powder particles together to obtain an almost fully dense material. Successive layers of metal powder par- ticles are melted and consolidated on top of each other resulting in near-net-shaped parts as found out by Kruth et al. (2004). Con- sequently, the laser melting and layered re-solidification of the powder particles is accompanied by the development of residual stresses, which arise from the high thermal gradients present in the material. This effect was discovered by Kruth et al. (2004). These stresses after Yadroitsev et al. (2013) can lead to part failure due to distortions, delamination or cracking. Besides the thermal stresses, the balling effect is also a severe impediment to interlayer connec- tion. A last phenomenon encountered which was first described by Kruth et al. (2005) is the vaporization effect which occurs when the powder bed is irradiated with high energy intensities. A lot of efforts are conducted to identify the crucial process parameters of SLM which influence the density of the parts as for example the work done by Mumtaz et al. (2008) on Waspaloy ® . The process is so far validated for a small range of different mate- rials such as different steels, pure titanium, some titanium base http://dx.doi.org/10.1016/j.jmatprotec.2014.04.002 0924-0136/© 2014 Elsevier B.V. All rights reserved.