Characterization of Cr–Al–C and Cr–Al–C–Y films synthesized by High Power Impulse Magnetron Sputtering at a low deposition temperature

• The films deposited at 450 °C both contained the MAX phase and solid solution.
• The films were polycrystalline with (110) texture, and columnar growth.
• Film stress was compressive in the a–b plane and tensile perpendicular to this.
• No difference was found in this result upon the introduction of up to 0.3 at.% Y.
• Introduction of a film structure model based on XRD, EDX, SEM and magnetic results

A focus point in this work was the study of the influence of a low substrate temperature, as well as the minor addition of Y (0.1–0.3 at.%), on the formation of the stable Cr2AlC–MAX (ternary alloy with general formula Mn + 1AXn: M = early transition metal, A = A-Group element, mostly IIIA or IVA, X = C or N, n = 1–3) phase. The coatings, deposited by High Power Impulse Magnetron Sputtering, consisted of a mixture of disordered solid solution (Cr,Al)2Cx and ordered Cr2AlC–MAX phase. All deposited coatings without and with 0.1–0.3 at.% Y addition were polycrystalline, and showed (110) texture and a columnar morphology. The measured strong lattice distortions along with the existence of the texture in the as-deposited samples indicate that compressive stress acts in the a–b plane and tensile perpendicular to this. A schematic model of the structural and chemical changes in the as-deposited layers due to deposition inhomogeneity and low deposition temperature, based on the X-ray diffraction, energy dispersive X-ray, scanning electron microscopy and magnetic measurements has been developed.