Growth kinetics of ceramic grains during liquid phase sintering in Mo2FeB2-based cermets

Mo ₂FeB ₂ -based cermets with different hard phases were fabricated by reaction boronizing sintering. SEM, EDS, and TEM were utilized to evaluate the growth kinetics of Mo ₂FeB ₂ hard-phase grains with different morphologies during liquid phase sintering. During the sintering stages of L ₁ and L ₂ , the growth of elongated grains along the long-axis conformed to the cubic law. Combined with the observed rough interface between the hard and binder phases, the growth mechanism along the long-axis could be identified as diffusion-controlled since atoms did not have to overcome large energy barriers to nucleate. Meanwhile, the grain growth along the short-axis was primarily accomplished via 2-D nucleation on the smooth interface, which was mainly controlled by interface reaction during the liquid phase sintering since the driving force in the short-axis direction failed to meet the requirements of critical driving force (∆ G _c). In addition, the principal control mechanism of nearly equiaxed grains growing in L ₁ and L ₂ was identical to the long-axis direction of elongated grains. Nevertheless, the third phase (Fe ₂₃B ₆ ) at the interface of nearly equiaxed grains affected grain growth, resulting in variations in grain size and growth activation energy during the L ₁ and L ₂ sintering stages.