This study focuses on developing a new processing route for ferrous matrix composites reinforced with niobium carbide by producing the reinforcement particles in situ using powder metallurgy. The aim is to improve the interfacial adhesion between matrix and reinforcement compared to traditional ex situ methods. Computational thermodynamics and kinetic analysis were used to optimize the raw materials and processing parameters. The raw materials are mixed, uniaxially pressed, and sintered in a tubular furnace. The study finds that liquid phase sintering improves densification but also leads to clustering, niobium-free regions, and abnormal grain growth. The optimal combination of porosity and microhardness is 16.5 ± 0.7% and 952 ± 82 HV0.05, respectively. Although there is room for further adjustments in processing, this study lays the groundwork for creating valuable materials using Brazilian strategic raw materials and technology.

In situ composite manufacturing techniques can improve the bond between the matrix and reinforcements in a composite material. This is achieved by creating the reinforcements within the matrix through the reaction of precursor materials, which form the desired phases. Thermodynamic data and simulation tools can be used to validate the process and design variables, saving time and resources. The aim of this study is to apply a theoretical framework developed by the authors to the development of a Fe-NbC in situ metal matrix composite. The framework involves using Gibbs free energy and dissociation criteria of reinforcements to validate the feasibility of the composite system and to assess composite formation kinetics and microstructural features based on the driving force and diffusion of elements in raw materials. Here, we demonstrate the application of these tools to the development of a Fe-NbC composite, starting from validating the feasibility to selecting between elemental powders, solid solutions, and intermetallics to achieve the desired microstructure.

In situ composite manufacture is an approach to improve interfacial adhesion between matrix and reinforcements, in which reinforcements are synthesized along composite processing itself. In situ powder metallurgy route, in particular, offers alternatives to some shortcomings found in other techniques. This work aims not only to review the state of the art on metal matrix composites (MMCs)—including cermets—obtained in situ by powder metallurgy, but also to dissect key aspects related to the development of such materials in order to establish theoretical criteria for decision making before and along experiments. Aspects regarding the design, raw material selection, and processing of such composites were observed and divided between concept, intrinsic, and extrinsic parameters. That way, by means of material databases and computational thermodynamics applied to examples of the reviewed literature, we aim at providing tools in both conducting leaner experiments and richer discussion in this field.