###### Abstract  
This study compared the microstructures and mechanical properties of nickel-chromium-molybdenum (Ni-Cr-Mo) alloys prepared from a single alloy with an identical composition using two new digital processes (selective laser melting (SLM) and soft metal milling (SMM)) and conventional lost-wave casting (LWC). Disc specimens were used to study the microstructures via various analytical methods, while dumbbell-shaped specimens were subjected to tension to determine the mechanical properties (\(n=6\)). The SLM and SMM alloys showed a higher number of large and small pores, respectively, than the LWC alloy. A face-centered cubic (\(\gamma\))-phased matrix was indexed for all three resultant alloys. The SLM and SMM alloys also showed more homogeneously distributed elements and finer grains (in particular, ultrafine grains in the SLM alloy) when compared to the LWC alloy. Meanwhile, the LWC alloy showed a statistically higher yield strength than the other two alloys (\(p<0.001\)). Notwithstanding, all three resultant Ni-Cr-Mo alloys satisfied the ISO 22674 standard criteria for type 5 materials (yield strength: \(>\)500 MPa; percentage elongation: \(>\)2%; and elastic modulus: \(>\)150 GPa).  
nickel-chromium alloy; selective laser melting; soft metal milling; mechanical properties 40.0000-0001-5000-00001-5000-0000  
Ni-Cr alloys are still widely used to fabricate the framework of metal-ceramic prostheses due to their low cost, high mechanical strength, favorable corrosion resistance, and relatively favorable biocompatibility [5; 6]. Traditionally, Ni-Cr metallic substrates have been prepared by the LWC technique. However, this process requires complex, multistep procedures and highly skilled dental technicians [7; 8]. Due to the recent development of new manufacturing techniques, Ni-Cr dental alloys can also be prepared using computer-aided design and manufacturing (CAD/CAM) systems. In general, these technologies can be classified as subtractive or additive manufacturing (SM or AM) approaches.  
AM processes have grown in popularity over the last decade, mainly due to their ability to produce complex shapes and reduce material waste. According to ISO/ASTM 52900 [9], AM technologies include seven process categories. In the case of metallic materials, the two available AM technologies are directed energy deposition and powder bed fusion (PBF) [10]. PBF methods include electron beam melting (EBM) and selective laser melting (SLM) for building three-dimensional (3D) structures [10; 11]. Parts fabricated by SLM are known to show improved mechanical and corrosion properties over their cast counterparts [12]. Moreover, the high cooling rates with SLM can produce much finer microstructures, and the materials are generally stronger and less ductile when compared to EBM [10; 12], whereas among the metallic SM processes, milling a hard and solid blank can minimize the occurrence of casting defects [13]. However, the milling performance can be significantly impaired due to the high rigidity of the solid metallic blanks and increased tool and machine wear [14]. Another recent SM technique, extensively applied in the biomedical and dental fields, is soft metal milling (SMM), where a pre-sintered metallic blank is soft-milled and subsequently sintered to the final full density [13]. However, comprehensive data on the properties of Ni-Cr alloys produced via the SLM or SMM manufacturing techniques remain limited.  
Accordingly, the present study evaluated the mechanical properties of nickel-chromium-molybdenum (Ni-Cr-Mo) alloys prepared via two new digital manufacturing methods (SLM and SMM) and with the conventional LWC technique. A single Ni-Cr-Mo alloy, with the same composition, was subjected to the three different fabrication methods to avoid the potential effect of minor alloying elements on the resultant alloy properties and to focus on evaluating the effect of the manufacturing techniques [15].