Ravi Sankar Kottada

The B2-Aluminide matrix (FeAl and NiAl) with in-situ Al2O3 reinforcement were synthesized using reactive milling. The oxides (Fe2O3 and NiO) were reduced by Al during high energy milling to form Al2O3. The 20 h ball milled powders were consolidated using spark plasma sintering (SPS). To understand the densification mechanisms during SPS, sintering was performed at various temperatures (750–850 °C) and applied pressures (25–100 MPa). The creep parameters are evaluated from the densification data obtained during SPS using the model proposed by Bernard and Granger. In addition, independent constant-stress compression creep studies were conducted on the dense SPS pellets. The creep studies were performed on the composites at 800 °C at different stresses (100–500 MPa). The densification studies and compression creep studies are correlated based on the creep parameters obtained from both these studies and corroborated by TEM studies of the crept samples. This correlation is found to be valid even for the in-situ composites. Thus, the analysis of densification data can be helpful in predicting the creep behavior and useful for designing the new creep resistant alloys or composites.

The densification kinetics during spark plasma sintering (SPS) of FeAl and NiAl powders were analyzed using a model proposed by Bernard-Granger and Guizard [10]. Creep parameters obtained through densification data are in good agreement with those obtained from conventional creep experiments. Validity of the model was illustrated for aluminides in the form of deformation mechanism maps. This validation assures plausible confidence to predict creep behavior using densification data obtained during pressure assisted sintering of metallic alloys.