An Experimental Study On The Mechanical Properties And Ternary Phase Diagram Of Ti-Si Alloys With Different Alloying Elements

Microstructure and mechanical properties of Ti-Si-Al-La alloys is observed. The results identified the best ratios of ingredients of Ti, Si, Al and La have been. By adding the alloying elements, the microstructure, mechanical properties and phase relationships have been studied deeply.With various content of La addition to the Ti-Si-Al alloy has been observed, the Ti-Si-Al alloy sample has the best microstructures and mechanical properties. Based on it, the influence of Nb on the microstructures and mechanical properties of the Ti-Si-Al-La alloys have been investigated by adding the alloying element Nb. Moreover, the RE (Y, La)-Ti-Si alloy phase diagram of the 500℃isothermal section have been studied.The experimental results show that the microstructures, mechanical properties and fracture mechanisms of Ti-Si-Al-La alloys have been improved with rare earths (RE) La. However, excessive RE (La) may deteri orate the mechanical properties.Based on the research of Ti-Si-Al-La alloys, the the microstructures, mechanical properties and fracture mechanisms of Ti-Si-Al-La-Nb alloys have been studied.The phase relationships in the Y-Ti-Si ternary system at 773 K have been investigated mainly by means of X-ray powder diffraction (XRD) with the aid of scanning electron microscope (SEM), optical microscopy (OM) and differential thermal analysis (DTA). The isothermal section consists of 12 single phase regions, 21 binary phase regions and 10 ternary phase regions. A binary compound Y₂Si₃ has not been found in this work at the present condition. Therefore, there are 9 binary compounds exist in the system in all, which are Y₅Si₃, Y₅Si₄, YSi, Y₂Si₃ and Y₃Si₅, Ti₃Si, Ti₅Si₃, Ti₅Si₄, TiSi and TiSi₂. No ternary compound is found in the work.In addition, the phase equilibria of the La-Ti-Si ternary system at 773 K have been investigated mainly by means of X-ray powder diffraction (XRD) with the aid of scanning electron microscopy (SEM), optical microscopy (OM) and differential thermal analysis (DTA). The isothermal section consists of 14 single phase regions, 25 binary phase regions and 12 ternary phase regions. The binary compounds Ti₅Si₄ and La₂Si₃ are confirmed at 773 K. Therefore, there are 11 binary compounds in the system, which are La₅Si₃, La₃Si₂, La₅Si₄, LaSi, La₂Si₃, LaSi₂, Ti₃Si, Ti₅Si₃, Ti₅Si₄, TiSi and TiSi₂. No ternary compound is found in the work.