## 1 Introduction  
Additive Manufacturing (AM) offers great promise to the medical [1], aerospace [2], automotive and defense fields [3; 4; 5]. It provides the advantage of building complex geometries by fabricating 3D objects one layer at a time using rendered CAD models [6], as a result, several techniques of AM have been developed, including, Electron Beam Melting (EBM) [7], Selective Laser Sintering (SLS) [8], Selective Laser Melting (SLM) [9], and Direct Metal Laser Sintering (DMLS) [10]. Another advantage of AM lies within the wide range of materials that can be manufactured such as plastics [11], metals [3; 12; 13; 14], ceramics [15], concrete [16] and fiber reinforced polymers [17], among others. The AM of metals are of particular interest to the production of dental implants, aerospace components, and automotive structures [18]. Today, stainless steel [19; 20], nickel alloys [21; 22], aluminum alloys [23; 24] and titanium alloys [25; 26] are common materials for metals AM. DMLS is one of the most common AM processes for 3D printed metals because it maintains dimensional control while producing complex features at high resolution [3]. There are two primary methods of manufacturing by DMLS: powder bed and powder deposition [27]. Powder bed methods rely on a high energy source, typically a laser (although some similar systems use electron beams), to locally sinter or melt metal particles on a powder platform. New powder layers are periodically added while the platform is levelled to accommodate the addition of new material. The 3D model is constructed in a single vertical direction [6]. Alternatively, powder deposition directly deposits the metal powder and melts it in place using a high-powered laser [28]. Unlike the powder bed method, which is typically restricted to one type of alloy, powder deposition has the ability to include different metal powders for functionally graded materials [29]. This process however, also has a number of drawbacks. Parts produced via DMLS typically have poorer mechanical properties compared to those produced by traditional means, which has relegated the potential uses to prototypes and short-term tooling operations [30]. Incomplete powder melting often leads to very rough surface finish and porosity, which in addition to being aesthetically displeasing also compromises fatigue life and can be a significant issue for wetted surfaces of air and water craft [29; 31]. In addition, the rapid heating and effective quenching of the metal results in a highly martensitic microstructure in most alloys [32]. While this produces a material with a high yield strength, it is also intensely brittle [32]. Though the microstructure resists the formation of cracks, once the cracks themselves form, the propagation of the cracks is quite rapid [33]. The high temperature gradient involved in these processes frequently causes thermal stress that compromise the fatigue performance of metals produced by DMLS techniques. Titanium alloys such as Ti-6 Al-4V are commercially available for additive manufacturing. Due to its high strength to weight ratio and fracture toughness, it is an ideal alloy for a wide range of applications in the aerospace and biomedical engineering fields [34]. For instance, Ti-6 Al-4V alloy is used in dental laboratories for medical implants and prosthetics due to its corrosion resistance, high specific strength as well as its biocompatibility characteristics. AM also allows for the creation of porous titanium structures that help facilitating bone ingrowth and adhesion for implants [35]. Advances in topology optimization allows for hyper-efficient geometries to be produced exclusively through additive manufacturing. One notable example includes the Airbus A320 nacelle hinge bracket which was eventually produced by AM [36]. With the many advancements in the field of AM, the production of titanium parts has become economically viable.