Study of Selective Laser Melting of intermetallic TiAl powder using integral analysis

XRD analysis shows domination of the α2-Ti3Al phase in the initial powder, heat treated powder before SLM and in the developed samples. Some minor peaks of γ-TiAl are identified in SLM parts. EDS analysis confirms the effect of Al evaporation, which intensifies with laser energy input. IR-camera is used for optical monitoring of a single track formation. The geometry of the thermal emission field for different processing parameters is compared with the track geometry. The intensification of hydrodynamic instabilities accompanied by material rejection from the zone of powder consolidation with beam scanning velocity is found. For the first time the evaporation of Al for elevated laser energy input is clearly detected by the IR-camera. Mathematical modelling shows that the same elementary volume of SLM sample can be remelted several times during its fabrication depending on the SLM processing parameters and beam scanning strategy. The maximum values of calculated cooling rates are in the order of 106 °C/s. For the first time the thermo-cycling during SLM parts fabrication is confirmed experimentally by pyrometer measurements.