Microstructure, chemistry and mechanical properties of Ni-based superalloy Rene N4 under irradiation at room temperature

Abstract

a b s t r a c tNickel superalloys with cubic L1 2 structured c 0 (Ni 3 (Al, Ti)) precipitates exhibit high strength at high temperatures and excellent corrosion resistance when exposed to water. Unlike prior studies on irradiation damage of other Ni-based superalloys, our study on Rene N4 involves much larger c 0 precipitates, $450 nm in size, a size regime where the irradiation-induced disordering and dissolution kinetics and the corresponding mechanical property evolution are unknown. We report that under heavy ion irradiation at room temperature, the submicron-sized c 0 precipitates were fully disordered at $0.3 dpa and only later partially dissolved after 75 dpa irradiation. Nanoindentation experiments indicate that the mechanical properties of the alloy change significantly, with a dramatic decrease in hardness, with irradiation dose. Three contributions to the change in hardness were examined: defect clusters, disordering and dissolution. The generation of defect clusters in the matrix and precipitates slightly increased the indentation hardness, while disordering of the submicron-sized c 0 precipitates resulted in a dramatic decrease in the total hardness, which decreased further during the early stages of the intermixing between c 0 precipitates and matrix (<18 dpa). Controlling the long-range-ordering and chemical intermixing can be used to tailor the mechanical properties of Ni-based superalloys under irradiation.

Irradiation stability and induced ferromagnetism in a nanocrystalline CoCrCuFeNi highly-concentrated alloy

“…Despite the fact bulk equiatomic FeCo magnetic alloys were firstly synthesized around 1920s [72][73][74], this present work demonstrated that FeCo nanomagnets can be easily synthesized via thermal annealing at relatively intermediate temperatures (773 K) starting with a nanocrystalline CoCrCuFeNi HCA (as-deposited) and, more important, they remain thermodynamically stable at room temperature (which is a challenge to achieve on nanoscale magnetic materials field [75]). Another experimental observation is that the FeCo nanomagnets appear not to be stable under heavy ion irradiation, undergoing ballisticassisted dissolution and mixing [76,77]; however, they can be restored upon annealing after irradiation which suggests they are highly stable.…”

Effects of Cooling Rate on the Solidification and Microstructure of Nickel-Based Superalloy GTD222

“…In order to develop more efficient advanced solidification technology, a data base of superalloys on thermophysical properties is increasingly needed [3]. From a theoretical and industrial perspective, knowledge of superalloy solidification behavior is crucial for the controlling of the superalloy casting process [4]. In the casting of nickel-based superalloys, the mechanical properties of alloys are due to microstructure characteristics, such as a combined matrix γ phase and γ′ precipitation phase [5], dendritic width [6] and grain size [7].…”

Effects of Solidification Cooling Rate on the Microstructure of Nickel Based Superalloy GTD222

“…In order to develop more efficient advanced solidification technology, the data of superalloys on thermophysical properties are increasingly needed [3]. From a theoretical and industrial perspective, knowledge of superalloy solidification behavior is crucial for the controlling of superalloy casting process [4]. For the nickel based superalloys, the matrix of alloy named gamma phase (γ) and the precipitate phase is known as gamma prime phase (γ′).…”