Microstructure and mechanical properties of hot pressed Mo-Cr-Si-Ti in-situ composite, and oxidation behavior with silicide coatings

作者：Paul Bhaskar^*; Majumdar Sanjib; Suri A K

来源：International Journal of Refractory Metals and Hard Materials, 2013, 38: 26-34.

DOI：10.1016/j.ijrmhm.2012.12.005

• Hot press
• RMIC
• Oxidation
• SEM
• Pack cementation coating
• Activation energy

The present study deals with the synthesis of Mo-16Cr-4Si-0.5Ti (wt.%) alloy by means of the reactive hot pressing method. The microstructure of the synthesized alloy consisted of (Mo, Cr, Ti)(3)Si, and the discontinuous alpha-(Mo, Cr, Ti)(ss) phases. The isothermal oxidation behavior of the alloy was investigated in air at 1273 K for 50 h. The alloy exhibited superior oxidation behavior in comparison with single phase molybdenum alloys, because of the formation of SiO2 and Cr2O3 over the alloy surface. The flexural strength determined from three-point bend testing of single edge notch bend specimens was 615 +/- 15 MPa. The dominant mechanism of fracture was identified as transgranular mode of crack propagation. To extend the life of the alloy under oxidizing atmosphere, silicide based oxidation resistant coatings were developed, using halide activated pack cementation process. The kinetic behavior of growth of the coating was established and the activation energy of the coating process was determined to be 52.5 kJ/mol. Isothermal oxidation tests of the coated alloy at 1273 K for 50 h, revealed a small weight gain at the initial stages of oxidation followed by no change of weight, indicating the protective nature of the coating.

• 出版日期2013-5