The role of Nd on the microstructural evolution and compressive behavior of Ti–Si alloys

The Pseudo-Eutectic Microstructure and Enhanced Properties in Laser-Cladded Hypereutectic Ti–20%Si Coatings

“…Therefore, crystallization occurs by diffusion decomposition into a mixture of crystals of α-Ti + Ti 5 Si 3 phases that preceded the growth of the primary Ti 5 Si 3 phase and resulted in the growth of a pseudo-eutectic structure in the Ti-20%Si alloy. The X-ray diffraction (XRD) patterns shown in Figure 4 indicate that both the metal mold cast and laser-cladded materials, primarily composed of α-Ti and Ti 5 Si 3 phases without the Ti 3 Si phase, suggests that the peritectoid reaction, Ti 5 Si 3 + β-Ti → Ti 3 Si, was supressed.…”

“…Ti-Si alloys are currently attracting wide academic interest due to their attractive characteristics, such as lightweight, high specific modulus, hardness, corrosion resistance, and good biocompatibility [1][2][3]. The Ti 5 Si 3 intermetallic compound phase, which has a complex D88 hexagonal structure (Mn 5 Si 3 -type, a 1 /40.7444 nm, c 1 /40.5143 nm), has the highest melting temperature (2130 • C), highest hardness (11.3 GPa), and relatively high Young's modulus (225 GPa) among the five silicide phases, TiSi 2 , TiSi, Ti 5 Si 4 , Ti 5 Si 3 , and Ti 3 Si, that exist in the binary Ti-Si alloy system [4].…”

“…The Ti 5 Si 3 intermetallic compound phase, which has a complex D88 hexagonal structure (Mn 5 Si 3 -type, a 1 /40.7444 nm, c 1 /40.5143 nm), has the highest melting temperature (2130 • C), highest hardness (11.3 GPa), and relatively high Young's modulus (225 GPa) among the five silicide phases, TiSi 2 , TiSi, Ti 5 Si 4 , Ti 5 Si 3 , and Ti 3 Si, that exist in the binary Ti-Si alloy system [4]. Thus, it could act as a desired reinforcement phase to significantly increase the hardness of the ductile titanium matrix.…”

“…Evidently, the higher the Ti 5 Si 3 phase content, the higher the hardness of the Ti-Si alloy. Indeed, hypereutectic Ti-Si alloys dominated by Ti 5 Si 3 have received much attention in recent years, including applications as coating materials [2][3][4][5]. Nevertheless, the proeutectic Ti 5 Si 3 phase nucleated from the liquid metal may develop into coarse particles, and result in low toughness of the alloy, which could restrict its applications [2,4].…”

“…This study aims to achieve the refinement of the Ti 5 Si 3 eutectic phase as well as to suppress the nucleation of the primary Ti 5 Si 3 phase of a Ti-20 atom % Si hypereutectic alloy using laser cladding. It is envisaged that, due to the nature of laser processing, i.e., under rapid solidification conditions, this aim can be achieved.…”