Direct Fabrication of a Ti-47Al-2Cr-2Nb Alloy by Selective Laser Melting and Direct Metal Deposition Processes

Abstract

A Ti-47Al-2Cr-2Nb (at.%) material was fabricated using two laser-based methods, “Selective Laser Melting” (SLM) and “Direct Metal Deposition” (DMD), for potential uses in aircraft jet engines. Experiments were conducted under controlled atmosphere by changing the processing parameters. Optimal parameters were searched for this relatively low ductility material to prevent cracking due to built-up residual stresses during fast cooling. It was observed that these non-equilibrium cooling conditions were fast enough to generate ultra fine and metastable structures exhibiting high microhardness values. Post heat-treatments were successfully used to restore homogeneous lamellar or duplex microstructures and to relieve the residual stresses. A comparison of these two methods is provided in terms of powder requirements and of process parameters to achieve noncracked structures and fully dense materials.

Microstructure of γ-titanium aluminide processed by selective laser melting at elevated temperatures

“…In this study the SLM samples yield porosity and cracks as a consequence of lacking preheating in contrast to the SEBM samples. The alloy Ti-48-2-2 has also been investigated by Vilaro et al [15] using SLM and Laser Metal Deposition (LMD). Again, generation of crack-free specimens by means of SLM was not reported.…”

Influence of cooling rate on microstructure formation during rapid solidification of binary TiAl alloys

“…Some attempts on the AM of titanium aluminide alloys have been reported recently [4][5][6]. While many experimental data are available regarding the phase evolution during solid state heat treatments and subsequent quenching [1,[7][8][9][10], comparably little is known about microstructure formation during rapid solidification [11][12][13][14].…”

As-Fabricated and Heat-Treated Microstructures of the Ti-6Al-4V Alloy Processed by Selective Laser Melting

“…The description of the process is done elsewhere and is not repeated here. [2][3][4] Its success is directly linked with its ability to manufacture complex structures from a computer-aided design model and a wide range of materials in short delays without the need of expensive tools such as molds. Another advantage is that the powder bed is selectively molten; therefore, the nonirradiated powder can be fully recycled for further fabrication (''ecoconception process'').…”