摘要
The influence of irradiation temperature on phase transformation and mechanical behavior in nanotwinned high-entropy alloy thin films was systematically explored under helium ion irradiation. High-resolution transmission electron microscopy revealed a fluence-dependent FCC→HCP phase transformation, mediated by partial dislocation glide in a diffusionless transfer similar to the transformation-induced plasticity effect. The transformation exhibited strong temperature dependence; the HCP phase fraction increased steadily with fluence at room temperature, while irradiations at 300 °C accelerated the initial transformation but led to phase instability. Notably, films irradiated at higher temperatures exhibited greater irradiation-induced hardening, correlating with the stabilized HCP phase and modified defect structures. Helium bubble behavior also changed significantly with temperature, showing increased bubble growth, coalescence, and grain boundary segregation at high temperature. These results highlight the role of temperature in dictating phase stability and mechanical performance under irradiation, offering key insights for the design of radiation-tolerant HEA coatings for high-temperature environments
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•He irradiation induces FCC-to-HCP transformation in nanotwinned CoCrFeNi.•Low SFE facilitates diffusionless transformation via Shockley partial glide.•Temperature dictates the switch from stress-driven to recovery regimes.•Synergistic hardening from bubbles and HCP phase arises at 300°C.•Dynamic phase reversion and detwinning lead to softening at high fluence.