Effect of the impact energy on the chemical homogeneity of a (Ti,Ta,Nb)(C,N) solid solution obtained via a mechanically induced self-sustaining reaction

Abstract

A titanium-tantalum-niobium carbonitride solid solution, (Ti,Ta,Nb)(C,N), was synthesised in a planetary mill via a mechanochemical process that involves a mechanically induced self-sustaining reaction (MSR) from stoichiometric Ti/Ta/Nb/C mixtures that are milled under a nitrogen atmosphere. The influence of the spinning rate of the planetary mill, which determines the impact energy of the milling process, on the ignition time (t ig) of the MSR process as well as the chemical homogeneity of the final product was analysed. The results indicated that the dependence of t ig on the spinning rate followed a potential function with a potential factor of 4.85, implying a remarkable reduction in the milling time required to induce the self-sustaining reaction at increasing spinning rates (i.e., from 4200 min at 200 rpm to 15 min at 800 rpm). However, the chemical and structural characterisation of the obtained products at ignition without any extra milling treatment indicated that a single solid solution phase was only obtained at the lowest spinning rates (i.e., less than 300 rpm). At increasing rates, the relative amount of the intended solid solution phase continuously decreased, and new undesirable secondary phases were formed. Despite the long milling times required for the milling experiments that were performed at the slowest spinning rates, iron contamination from the milling media was negligible due to the low intensity milling regime.

Phase diagrams in alternative hard materials: Validation of thermodynamic simulation through high temperature x-ray diffraction, differential thermal analysis and microstructural characterization

“…Avoidance of heavy transition elements in Ti(C,N)-FeNi cermets has also led to CSS materials [143,151,199]. Last, through mechanochemical processing (MCP), (Ti,Mo)C and (Ti,Ta,Nb)(C,N)-based CSS cermets were synthetised from elemental powders [140,196,200,201]. Microstructural features -more specifically grain size and binder content -govern the properties and applications of the manufactured hard materials.…”

Effect of Milling Parameters on the Development of a Nanostructured FCC–TiNb15Mn Alloy via High-Energy Ball Milling

“…Concretely, the syntheses carried out by Garcia-Garrido et al [8,9] were possible by means of MA, which has been reported to be a simple, economic, and reproducible method, in the following ways: to extend the metal solubility; to produce complete solid solutions; to refine the structure up to nanometric levels, and to synthesize new crystalline phases, such as the novel high-entropy alloys (HEAs) [16], quasi-crystalline phases, and amorphous phases, among other interesting abilities [17]. With respect to MA, it has been established that not only the rate of the reaction, but also the reaction route and the products obtained, can be highly influenced by using different milling equipment and milling conditions [18][19][20].…”

Effects of Boron Addition on the Microstructure and Mechanical Properties of (Ti,Ta)(C,N)-Co Based Cermets

“…Recently, a new, simple, affordable, and reproducible mechanochemical method, denoted as mechanically induced self-sustaining reaction (MSR), has been successfully applied for the synthesis of complex solid solution carbonitrides with optimal stoichiometric control [18,19] and the development of cermets based on them. The MSR method is a reactive milling process that uses the exothermic nature of the carbonitride formation to synthesize them from the mixture of transition metal elements and a carbon source (usually graphite) under a reactive N 2 atmosphere.…”