Temperature-dependent deformation mechanisms influenced by the μ phase TCP in a Ni-based single crystal superalloy

The influence of the plate-like μ phases precipitates in Ni-based single-crystal superalloys on their mechanical properties and deformation mechanisms was systematically investigated over a range of temperatures (25–700 °C) using multi-scale mechanical testing together with electron microscopy-based microstructure analysis. Macro-scale compression tests provided insights into the bulk mechanical performance, whereas in situ scanning electron microscope (SEM) micropillar tests enabled direct comparison of local deformation behaviors between μ phase-containing and μ phase-free regions. The results demonstrated that at room temperature, the μ phase remained undeformed and acted as an effective barrier to slip propagation. However, at elevated temperatures ( 500 °C), the μ phase exhibited distinct deformation modes, including bending and shearing along non-basal planes. In contrast to the temperature-dependent deformation behavior, the critical resolved shear stress (CRSS) of micropillars consistently decreased in the presence of μ phases, irrespective of temperature. This indicates that the observed CRSS reduction likely originated from microstructural changes in the surrounding γ/γ’ rather than from deformation of the μ phase itself. ... mehrThis work clearly demonstrates temperature-dependent deformation behavior of the μ phase formed in Ni-based single-crystal superalloys and provides insights into a guidance for microstructural control and enhanced material reliability in high-temperature applications.