摘要
A composites of (Mo<sub>0.9</sub>Cr<sub>0.1</sub>)Si<sub>2</sub> + 15vol% ZrO<sub>2</sub> was prepared with powder metallurgy and Pressure- Less Sintering (PLS) method, aiming at applications of high temperature structural materials. Mechanical properties of the composites were assessed with hardness, indentation fracture toughness K<sub>c</sub> and K<sub>IC</sub> tested using SEVNB, flexure strength at room temperature and 1200?C, and isothermal oxidation at 1400?C. The results showed that the native silica oxide and molybdenum-oxides on the silicide feedstock surface were significantly reduced in terms of Cr-alloying. (Mo<sub>0.9</sub>Cr<sub>0.1</sub>)Si<sub>2</sub> and its composite also exhibited improved sinterability and grain growth, owing to the presence of (Cr, Mo)<sub>5</sub>Si<sub>3</sub> at grain boundaries. Fracture toughness of the composite was increased by a factor of 1.6 to that in the monolithic silicide. Mechanical property of the composite at high temperature was not affected by Cr addition. However, the high temperature oxidation resistance was greatly improved in the (Mo<sub>0.9</sub>Cr<sub>0.1</sub>)Si<sub>2</sub> + 15vol% ZrO<sub>2</sub> compared with the non Cr-alloyed counterpart. The Cr-alloying effects on the microstructure, fracture behaviour, and high temperature oxidation resistance were discussed.
A composites of (Mo<sub>0.9</sub>Cr<sub>0.1</sub>)Si<sub>2</sub> + 15vol% ZrO<sub>2</sub> was prepared with powder metallurgy and Pressure- Less Sintering (PLS) method, aiming at applications of high temperature structural materials. Mechanical properties of the composites were assessed with hardness, indentation fracture toughness K<sub>c</sub> and K<sub>IC</sub> tested using SEVNB, flexure strength at room temperature and 1200?C, and isothermal oxidation at 1400?C. The results showed that the native silica oxide and molybdenum-oxides on the silicide feedstock surface were significantly reduced in terms of Cr-alloying. (Mo<sub>0.9</sub>Cr<sub>0.1</sub>)Si<sub>2</sub> and its composite also exhibited improved sinterability and grain growth, owing to the presence of (Cr, Mo)<sub>5</sub>Si<sub>3</sub> at grain boundaries. Fracture toughness of the composite was increased by a factor of 1.6 to that in the monolithic silicide. Mechanical property of the composite at high temperature was not affected by Cr addition. However, the high temperature oxidation resistance was greatly improved in the (Mo<sub>0.9</sub>Cr<sub>0.1</sub>)Si<sub>2</sub> + 15vol% ZrO<sub>2</sub> compared with the non Cr-alloyed counterpart. The Cr-alloying effects on the microstructure, fracture behaviour, and high temperature oxidation resistance were discussed.
作者
Yiming Yao
Erik Ström
Xin-Hai Li
Qin Lu
Yiming Yao;Erik Ström;Xin-Hai Li;Qin Lu(Department of Materials and Manufacturing Technology, Chalmers University of Technology, Gothenburg, Sweden;Heating Systems Division, Sandvik Heating Technology AB, Hallstahammar, Sweden;Material Technology, Siemens Industrial Turbomachinery AB, Finspong, Sweden)
