Microstructural characteristics and elevated temperature wear of Ti-11Si-16Al alloy

Abstract

The microstructural characteristics and elevated temperature wear behavior of a Ti-11Si-16Al alloy have been investigated, compared with the as-cast Al-free Ti – Si eutectic alloy. Experimental results show that addition of 16 at.% Al greatly modifies the microstructure by forming near-equiaxed Ti5Si3, rod-like Ti3Al and rosette-like eutectic cells distributing on a continuous α-Ti (Al, Si) solid solution phase. Therefore, mechanical properties such as Vickers' hardness, elastic modulus and strength are significantly improved. In-situ hot pressing and sintering of the hybrid oxide particles form a compact-and-hard glaze layer on the worn surface of the alloy. It has protective effects on the Ti-11Si-16Al specimen by relieving oxygen diffusion, alleviating rubbing of the counterpart and providing a solid lubricant effect with the hybrid oxide particles. This effectively improves the elevated temperature wear resistance and friction stability.

Evaluation of Ti3Si Phase Stability from Heat-Treated, Rapidly Solidified Ti-Si Alloys

“…The steps of levitation, melting, and splat-formation were easily accomplished with these alloy compositions. Considering the reported sensitivity of phase equilibria in this system with respect to oxygen, the splats were separately encapsulated under argon in quartz tubes together with a significant amount of Ti fillets to act as an O 2 for various time ranging from 6 to 90 h. Upon conclusion of the experiments, the capsules were removed from the furnace and air cooled. The resultant materials had their microstructures characterized by x-ray diffraction (XRD), conventional scanning electron microscopy (SEM), and a selected sample via fieldemission gun-scanning electron microscopy (FEG-SEM), using in all cases back scattered electrons (BSE) to form the images.…”

“…Several of these alloys have compositions with significant amounts of Si [1][2][3][4][5] and thus, accurate knowledge of the phase relations in the Ti-Si system, especially in the Ti-rich region is of fundamental importance. The Ti-Si phase diagram shown in Fig. 1 [6] indicates the following stable solid phases in the Ti-rich region: (1) terminal aTi-hcp and bTi-bcc solid solutions; (2) Ti 3 Si; (3) Ti 5 Si 3 ; and (4) Ti 5 Si 4 .…”

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

“…Its good formability and low processing cost make it a very promising casting alloy. The strengthening mechanism of Ti-Si alloys differs greatly from the traditional titanium alloys [4][5][6][7]. It consists of a continuous ductile phase (Ti, as the matrix) and a brittle second phase (Ti 5 Si 3 , as the reinforcement).…”