Effect of annealing temperature on anisotropy of mechanical properties in powder metallurgy FeCoCrNiN0.07 high-entropy alloy sheets

Abstract

In this study mechanical properties and texture of powder metallurgy FeCoCrNiN0.07 HEA sheets were studied at cold-rolled and different annealed conditions. The results show that the sheets at the cold-rolled (CR) condition and annealed state at 500 °C (anneal-500) exhibit obvious anisotropy of mechanical properties and the strength along the rolling direction is lower than that in the 90° direction. This mechanical anisotropy reduces significantly in the sheet after annealing at 750 °C (anneal-750). The main texture components are F {111} <112>, Goss {110} <001>, G/B {110} <115> and E {111} <110> texture for the CR condition, and F {111} <112>, Goss {110} <001>, Brass {110} <112> and E {111} <110> texture for the anneal-500 condition, respectively. The mechanical property anisotropy of the FeCoCrNiN0.07 sheet could be well explained by the equivalent Schmid factors (ηsD) which are calculated by weighting the maximum Schmid factors (ηsmax) for different texture components along different loading directions using their volume fractions. The equivalent Schmid factors of CR and anneal-500 sheets in the 0° (rolling direction), 45° (an angle of 45° to the rolling direction) and 90° (perpendicular to the rolling direction) directions gradually decreased in order, which fits well with that the strengths in the 0°, 45° and 90° directions gradually increased in sequence. The anneal-750 sheet has undergone significant recrystallization and the anisotropy of mechanical properties is greatly reduced consequently.