Shizhong Wei

Characterization of Al2O3 in High-Strength Mo Alloy Sheets by High-Resolution Transmission Electron Microscopy.

A novel type of alumina (Al2O3)-doped molybdenum (Mo) alloy sheet was prepared by a hydrothermal method and a subsequent powder metallurgy process. Then the characterization of α-Al2O3 was investigated using high-resolution transmission electron microscopy as the research focus. The tensile strength of the Al2O3-doped Mo sheet is 43-85% higher than that of the pure Mo sheet, a very obvious reinforcement effect. The sub-micron and nanometer-scale Al2O3 particles can increase the recrystallization temperature by hindering grain boundary migration and improve the tensile strength by effectively blocking the motion of the dislocations. The Al2O3 particles have a good bond with the Mo matrix and there exists an amorphous transition layer at the interface between Al2O3 particles and the Mo matrix in the as-rolled sheet. The sub-structure of α-Al2O3 is characterized by a number of nanograins in the

Preparation and Properties of ZrO2/Mo Alloys

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The Mechanical Properties of the Mo-0.5Ti and Mo-0.1Zr Alloys at Room Temperature and High Temperature Annealing

direction. Lastly, a new computer-based method for indexing diffraction patterns of the hexagonal system is introduced, with 16 types of diffraction patterns of α-Al2O3 indexed.

Preparation and properties of high-strength molybdenum alloy sheets doped with Al2O3 particles

Abstract The nano-sized ZrO2 reinforced Mo alloys were prepared by hydrothermal synthesis and subsequent sintering. During preparation, the nano-sized ZrO2 particles were added into the Mo powder via hydrothermal synthesis. This work investigated the differences in mechanical properties and microstructures of the Mo-ZrO2 alloys prepared by hydrothermal synthesis and the other traditional method. As the amount of ZrO2 particles increased, the grain size of the Mo powders reduced obviously. The grains were refined obviously after sintering. The ZrO2 particles added by hydrothermal synthesis can effectively restrain the growth of grains and improve mechanical properties such as strength and hardness.

Tribological behaviors of B4C-hBN ceramic composites used as pins or discs coupled with B4C ceramic under dry sliding condition

Abstract Mo-0.5Ti and Mo-0.1Zr alloys were prepared by powder metallurgy. In Mo-0.5Ti and Mo-0.1Zr alloys, there appears the second-phase particles of Ti2O3 and ZrO2 respectively, each of which can effectively prevent the dislocation activity in the process of plastic deformation. The addition of Zr can increase the strength of molybdenum alloys. Meanwhile, the ZrO2 formed from the alloy element Zr can refine the grains of molybdenum alloys to improve the recrystallization plasticity. After annealing, the tensile strength decreases while the plasticity greatly increases compared to the annealed Mo-0.5Ti and Mo-0.1Zr alloys. With the increase of annealing temperature, both the tensile strength and plasticity of Mo-0.5Ti and Mo-0.1Zr alloys decrease. Compared with pure Mo, after annealing the properties of the Mo-0.5Ti alloy and the plasticity of the Mo-0.1Zr alloy significantly increases.

Preparation and characterization of Mo/Al2O3 composites

The pure molybdenum sheet and the Al2O3-doped molybdenum alloy sheets were prepared by the hydrothermal method and a subsequent powder metallurgy process. The effects of Al2O3 particles addition on the recrystallization temperature, microstructures and properties of the Mo sheets were investigated as the focus. The Al2O3-doped Mo sheets have greater strength than the pure Mo sheet, and the 0.50xa0wt% Al2O3-doped Mo sheet has the best performance. For the unannealed specimens, the strength increases with the increase in Al2O3 content. Compared with that of pure Mo sheet, the strength of 0.50xa0wt% Al2O3-doped Mo sheet increases by 72xa0%, 54xa0%, 73xa0% and 76xa0%, respectively, when annealed at 1000, 1100, 1200 and 1300xa0°C, which is a very obvious reinforcement effect. When lower than 1100xa0°C, the elongation of the pure Mo sheet is the best. However, when the annealing temperature is equal to or greater than 1100xa0°C, the 0.50xa0wt% Al2O3-doped Mo sheet obtains the best elongation. Moreover, the Al2O3 addition can greatly improve the recrystallization temperature of molybdenum sheets; for example, the recrystallization temperature of the 0.50xa0wt% Al2O3-doped Mo sheet increases by 200xa0°C at least than that of the pure Mo sheet. Lastly, the strengthening mechanism was discussed.