High-temperature mechanical properties and fatigue of nanocrystalline nickel-cobalt-phosphorous (NiCoP) alloy

Nanocrystalline (nc) alloys, owing to their high strength, have been extensively studied over the past few years. High-temperature mechanical properties including tensile and fatigue were studied for commercially obtained nc nickel-cobalt-phosphorous (NiCoP) alloy through a novel mechanical testing setup. The Joule heating technique was used to enable high-temperature testing to 300 °C. The nc NiCoP was observed to maintain 90% of its strength to 130 °C and had > 1 GPa tensile strength up to 200 °C. Fatigue performance showed a minimum degradation between room temperature and 200 °C with an endurance limit of 750–825 MPa. Microstructure characterization revealed abnormal grain growth leading to fatigue fracture.