Penetrator in refractory and ductile high entropy alloys – ESTOCADE

The project ESTOCADE aims to develop a new generation of refractory material for kinetic penetrator. The penetration performance to be look for is to be superior to the performance of the tungsten alloys commonly used by the French army. This new generation is to be generated, without the environmental constraints associated with the depleted uranium, known as being the most performant material with regard to penetration.

The project ESTOCADE was build on the results of a CIFRE defense thesis and a DGA contract on a new generation of refractory alloys with the High Entropy Alloys (HEA), identified by their potential to outperform conventional tungsten alloys, or even be equivalent to depleted uranium alloys. From these results we identify three main barriers that we propose to overtake, from the realization of a model prepared in the ICB laboratory ICB (TRL3) to the obtention of a prototype elaborated by SINTERMAT (TRL6), with the evaluation of the penetration performance by NEXTER MUNITIONS. In order to address the kinetic penetrator requirements, the objective of the first barrier is to develop ductile HEA of density greater than 17g/cm3, by associating a thermodynamic approach using the THERMOCALC tool, a characterization of the microstructures, and a measurement of the tensile properties. The second barrier has an optimization objective through an analysis using Artificial Intelligence of physical and mechanical characteristics of 12 HEAs developed in the previous step. Finally, the third barrier address the elaboration of long rods to answer the requirements of kinetic penetrator, i. e. to master the scaling up.

The close manufacturing of long kinetic penetrator, 200 mm for the medium caliber ammunitions of the Jaguar armored vehicle and up to 800 mm for the large caliber ammunitions of the Leclerc tank, with controlled microstructures is a major challenge for the industry. With today production means, for tungsten alloys the final product is obtained through sintering and swaging, and starting from a from foundry raw material for uranium alloys; the materials present heterogeneity in terms of grain size, therefore in mechanical properties. The environmentally friendly approach adopted by the ESTOCADE project partners is to move towards lean consumption of raw materials, rapid and controlled heating and cooling to reduce the environmental impact with an energetic consummation reduce by 25 to 35%. This challenge can be answered with the use of the Spark Plasma Sintering technology, mastered by ICB and SINTERMAT.

This project includes two ambitious criteria of success. The first success criterion focuses on the acquisition of ductile HEA with a density of 17g/cm3. The second success criterion address the identification of HEAs with failure mechanisms in compression initiated by adiabatic shear bands, recognized mechanisms linked to the penetration performance. After reaching these two criteria, the objective will be quantified through the measurement of intrinsic penetration performance with terminal ballistic tests. At the international level, to our knowledge, none of the leading countries in this field has implemented an equivalent project.

The project is register within the field « ground combat » which objective is to generate the necessary technologies for the future ground weapon systems, through the acquisition of novel kinetic penetrators. Civil prospect is about refractory alloys used in the International Thermonuclear Experimental Reactor ITER, but also on the use of refractory metals and composites (W, Ta, TaW2,5) in CERN research.