Design, powder metallurgy, sintering, and softwares for extremely hard multicomponent metal alloys

Extremely hard multi-component metal alloys (EHMMAs) are required mainly when wear resistance is the most important requirement in a product. In view of this, researchers established some technical parameters to predict the stability of the resulting EHMMA and facilitate the design process of this alloy. Among the existing parameters, twenty-two were selected in this research to theoretically intend to ensure that EHMMA forms a stable solid solution. Associated with some of these parameters, there are five criteria from which the stability of the alloy is evaluated. Aiming to predict, streamline and facilitate the EHMMA design process, concomitantly with the calculation of the parameters involved and the availability of the status of the associated criteria, three softwares (PComp, DIAMOY 2.0, and SINT) were coded in Microsoft Visual Basic 6.0® and transformed into Windows® applications. The first one developed, the PComp, provides the minimum load necessary to compact the alloy powder, outlining, streamlining and trying to guarantee less porosity in the compacted for later sintering. The second software, DIAMOY 2.0, addresses the mass of each chemical element to compose the required EHMMA mass, in addition to calculating the values of twenty parameters and five associated criteria, and whether each established criterion is met. Depending on the results, this software can avoid laboratory experiments with alloys that would not present the possibility of constituting stable solid solutions associated to high hardnesses. The scheme of the experimental part of this thesis is translated into a flowchart of the process, in which nine different alloys are studied in terms of their obtainment, hardness, chemical composition, densification, and microstructure. As part of the results, the alloys are subjected to scanning electron microscopy (SEM), backscattered electron (BSE), and differential scanning calorimetry (DSC). Hardnesses up to 1054.96 Vickers were obtained. The maximum densification reached 98.54% of the theoretical. The results from DIAMOY 2.0 were validated by comparing two EHMMAs with a maximum relative error of 1.923% for one EHMMA and 3.183% for the other EHMMA. The third software, SINT, was developed to evaluate the densification of metal alloys and was applied to L4 alloy. Therefore, the main contributions of this research to the design of EHMMAs refer to: (a) gathering of parameters and criteria not yet used for the design of EHMMAs in a single computational tool, facilitating the evaluation of the design process; (b) establishing an EHMMA design framework; (c) creation of computational tools for powder compaction, EHMMA design and sintering for Windows® platform; (d) creation of metallic alloys not yet reported; (e) carrying out experiments with some alloys that have a predicted potential to form stable solid solutions with high hardness; (f) establishing a baseline for future improvements.