నైరూప్య

Thermodynamic calculations describing the solidification of a {m,m�?�?�?�?�?�?�?�?}-based {30Cr, 1C, 15Ta} containing alloy and microstructure Comparison with the alloy really elaborated. Part 3: {m,m�?�?�?�?�?�?�?�?}={Fe,Ni}

Kevin Duretz, Ga�?�?�?�?�?�?�?«l Pierson, Patrice Berthod

In this third part of this work this is the case of a FeNi30Cr1C15Ta alloy which is examined. Here too the study began with thermodynamic calculations which described the successive sequences of solidification and solid state transformations. The real alloy was then elaborated and metallographically characterized. Itsmicrostructure is composed of a dendritic matrixmainly composed of an austenitic phase but also containing dispersed areas of a ferritic phase butwithmuch lower fraction.Carbides are exclusively tantalumcarbides but of two types. Compact TaC particles have appeared at the beginning of solidification and script-like TaC carbides mixed with the matrixwere formed at the eutectic part of solidification. In this third alloy too the high contents in carbon and tantalum did not lead to high hardness value since the supplementary carbides, by comparisonwith the ones usually obtained for half quantities in C and Ta, are not-interconnected compact particles.