Effect of Annealing Treatment on Precipitates and Tensile Properties of FeCoCrNiVN High-Entropy Alloy Produced by Twin-Roll Casting

In the present work, an as-cast strip of novel high entropy alloy (Fe48.8Co26.9Cr9.7Ni5.7V8.3N0.6 at.%) was successfully produced by twin-roll casting technology. Then, the as-cast strip with or without primary annealing was cold-rolled and annealed. The directly cold-rolled and annealed samples consisted of single-phase FCC and they were easier to recrystallize. While many granular VN particles precipitated during primary annealing. Besides, after secondary annealing, the dual phases microstructure of FCC+BCC was obtained. The BCC phase made the alloy have high recrystallization resistance and inhibited grains growth, causing refined grains in secondary annealed samples. The grain size was refined to 1.26 mu m when annealed at 800 degrees C, the corresponding recrystallization fraction was only 60.9%. When annealing at 1000 degrees C, the content of BCC decreased, resulting in larger grain size (similar to 8.13 mu m) and fully recrystallized structure. The secondary annealed sheets showed excellent tensile properties, the ultimate tensile strengths were 770-898 MPa and corresponding total elongations were 32-46%.