Formation mechanism of coronal composite secondary phase in titanium-zirconium-molybdenum alloy

Abstract

The coronal composite secondary phase has a high mismatch tolerance with the molybdenum matrix. TiO 2 particles located within the coronal structure that provide a semi-coherent interface with a mismatch degree of 8.70%, and ZrO 2 particles located outside the coronal structure that provide an incoherent interface with a mismatch degree as high as 41.61%. The ZrO 2 particles of the coronal composite secondary phase are partially attached to the TiO 2 in a coronal structure, which endows the ZrO 2 with the molybdenum matrix's higher interfacial bonding force. Titanium sulfate and zirconium nitrate are realized the mixing of Ti/Zr, TiO 2 /ZrO 2 molecules at atomic levels. Compared with Ti, Zr is more easily combined with oxygen, which leads to Zr in Ti/Zr solid solution being attracted by oxygen at high temperature to form ZrO 2 . The small addition of zirconium element lacks nucleation particles to form of ZrO 2 , so ZrO 2 can only adhere to more TiO 2 particles and nucleate, forming the second phase of the coronal composite structure. This study can guide the design of high-performance secondary phase strengthening alloys. • The coronal composite secondary phase and the Mo matrix have a high tolerance of mismatch degree. • ZrO 2 particles are attached to TiO 2 , which endows ZrO 2 with a higher interfacial bonding force with Mo. • The secondary phase particles have a fine particle size, uniform distribution, and strong adhesion. • Mixing at the molecular or atomic level, Zr is oxyphilic, enabling the formation of the coronal composite secondary phase.