Spark Plasma Sintering Densification Behavior of the K4202 Alloy and Its Mechanical Properties

As a near-net forming method, the spark plasma sintering (SPS) process could quickly compact the alloys and refine the grains, indicating significant advantage in preparing of precipitation-strengthened superalloy. In this article, the K4202 superalloy was prepared using the SPS process. During sintering, the powders leakage and mold damage occurred when the sintering temperature exceeded 1100 °C. To solve this problem, the macroscale model containing sintered body and graphite molds, as well as the microscale model analyzing powder particles, were both calculated under finite element method. Based on the simulation and experimental results, the sintering process was optimized and the mentioned defects were overcome using the adjusted loading curve. In addition, the densification behavior of the alloy has been discussed in detail. It is noted that the local temperature rise is beneficial for the migration of materials and diffusion of atoms, which could facilitate the formation and flattening of sintering necks. The mechanical properties of the prepared alloy were further optimized by heat treatment, and the results show that the large amount of γ′′ phase generated after aging could significantly strengthen the alloy.