Long-term Thermal Stability and Evolution of Ni-rich Laths in Cr-alloys

Le résumé fourni par la source

Interest in Cr-based alloys for high-temperature structural applications has re-emerged due to their high melting points, low density, and excellent corrosion resistance [1–4]. However, maintaining mechanical stability at elevated temperatures remains a key challenge, as many Cr-based systems exhibit high-temperature softening [4,5]. While precipitation strengthening has been explored as a potential solution, the long-term thermal stability of strengthening phases in Cr-based alloys remains poorly understood. Here, we present preliminary results on the high-temperature stability and evolution of intermetallic Ni-rich laths in a binary Cr-Ni alloy. Using correlative scanning electron microscopy (SEM), transmission electron microscopy (TEM), neutron diffraction, and hardness testing, we investigate its long-term thermal stability after prolonged thermal exposure at 760 °C up to 1000 h. Our findings indicate that while this phase initially enhances strength, extended aging at elevated temperatures leads to morphological and structural changes that contribute to a gradual loss of strengthening capability. These observations highlight the stability limitations of Cr-Ni strengthening phases and emphasize the need for further research into enhancing their long-term performance in extreme environments, providing key insights for the design of next-generation high-temperature Cr-based alloys.

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