Production of High Entropy Alloy CoCrFeNiMo_x targets for magnetron sputtering via Cold Spray

Production of High Entropy Alloy CoCrFeNiMo_x targets for magnetron sputtering via Cold Spray

Production of thin film coatings are commonly effectively achieved via sputter coating techniques, and this has been demonstrated to remain true for high entropy materials. However, production of high purity bulk HEA sputter targets can be challenging. The direct casting of these alloys is often unsuitable, due to elemental segregation or phase separation occurring on slow solidification. For this study we used cold spray deposition to apply two different HEA alloys onto copper substrates. These materials had two different but very similar elemental compositions, however the primary crystalline phases present at equilibrium for each material differed significantly between BCC and FCC. While FCC phase material proved readily sprayable, the BCC phase material demonstrated the typical brittleness of BCC metal alloys, posing significant challenge to achieve sufficient deposition efficiency.