Crystal orientation and phase structure transitions in multi-layer extreme high speed laser claddings (EHLA) of eutectic high entropy alloy (EHEA) AlCoCrFeNi2.1

High entropy alloys (HEAs) present distinct advantages over conventional single-principle-element alloys. Eutectic high entropy alloys (EHEAs) allow utilization of two distinct HEA phases in one bulk, leading to further enhanced mechanical properties. Extreme high speed laser cladding (EHLA) allows for rapid production of low-dilution EHLA layers with low heat-affects on low-value components.

Presently, EHLA EHEA AlCoCrFeNi_2.1 cladding layers were produced on ductile cast iron substrates. Cladding cross-sections demonstrated eutectic phase structure transformations in response to EHLA process parameters. EHEA phases were predicted via thermodynamic calculations. Phase fractions in AlCoCrFeNi_2.1 powder and claddings were characterized via X-ray diffraction (XRD) with Rietveld fitting. Cladding mechanical properties were characterized via micro- and nano-hardness mapping.

Various crystal orientation relationships were observed. Electron backscatter diffraction (EBSD) was used to characterize a) the presence of eutectic structures within feedstock powders, b) the propagation of said structures across multiple cladding layers, and c) the influence of EHLA thermal cycles on EHEA cladding structures.

The work demonstrated advantageous phase structure transitions in response to input cladding parameters. Potential was identified for microstructural and mechanical property tailoring of EHLA claddings produced with a single EHEA powder feedstock.