Novel Ti-Based Nanocomposites by Selective Laser Melting (SLM) Additive Manufacturing (AM): Tailored Nanostructure and Performance

Abstract

Selective laser melting (SLM) additive manufacturing (AM) process was used to produce nanocrystalline TiC-reinforced Ti matrix bulk-form nanocomposites. The influences of laser energy density on densification activity, microstructural feature, nanohardness, and wear behavior of SLM-processed parts were comprehensibly studied to improve the controllability SLM process of nanomaterials. The TiC reinforcement in SLM-processed nanocomposites typically had a unique nanoscale lamellar structure, which was distinctly different from the initial particulate morphology before SLM. Reasonable physical mechanisms and conditions for the formation of TiC nanostructure reinforcing phase during SLM process were proposed. The microstructural and mechanical properties of SLM-processed TiC/Ti nanocomposite parts were sensitive to the preparation method of the starting nanocomposite powder and the content of TiC nanoparticles. The optimally processed TiC/Ti nanocomposite parts by SLM demonstrated the significantly elevated microhardness and wear performance as relative to the unreinforced Ti parts. IntroductionTitanium (Ti) and its alloys, due to high specific strength, sufficient stiffness, and excellent corrosion resistance, have been widely used in the aeronautical, chemical, and biomedical industries [1,2]. However, the limited wear resistance of Ti is a serious concern for the application environments where abrasive and erosion phenomena exist [3]. Considerable research attempts, accordingly, have focused on the application of various surface modification techniques to prepare ceramic particle reinforced Ti matrix composites (TMCs) coatings to improve surface properties of Ti. In particular, laser processing methods such as laser melt injection [4], laser cladding [5], and laser surface alloying [6] have demonstrated a considerable efficiency in preparing high-performance TMCs coatings. Laser processing normally offers high heating/cooling rates (10 3 -10 8 K/s) for the development of nonequilibrium phases with fine-grained microstructures and novel properties [1]. Furthermore, TMCs have been realized as bulk-form components, typically through powder metallurgy (PM) [7] and casting [8] methods, and afford more significant advantages in industrial applications.