Integrated Computational Materials, Process and Product Engineering – IC-MPPE 2022

Compositionally Complex Alloys (CCAs) are a part of the High Entropy Alloy (HEA) concept, which currently draws much attention from both fundamental and applied research perspectives. For advanced high temperature applications, these alloys, strengthened by intermetallic particles, show high potential for replacing some types of state-of-the-art Ni-based superalloys in the future. Such alloys can be widely used in hot regions of high performance aircraft turbines. Within this application area, the need for novel materials with high yield strength, exceeding the strength levels of existing alloys for application at temperatures above 649°C, is strong. Materials that can withstand extreme conditions at even higher temperatures are needed to provide a better energy efficiency of the turbine engines by reduced fuel consumption.
In this work, we assess the potential of novel wrought CCAs, designed on the base of the state of the art alloy design concepts and predictive computational approaches. The composition of the new alloys was selected with the help of density functional theory (DFT) calculations and a newly developed DFT-based software toolkit (Material Design Toolkit) supporting high throughput calculations of multicomponent alloys with various degrees of compositional and magnetic disorder. The predictive power of the MDT has been assessed in a series of experiments and used in design of new CCA compositions.
Newly produced alloys have been characterized using high resolution microscopy investigations. The mechanical properties have been assessed using high temperature compression tests and comparing them to existing analogous commercial alloys. The results show that the designed alloys can reach very promising compressive yield strength at the application temperatures of 649°C and 800°C, surpassing conventionally used Ni-based alloys. Additionally, a potential of improved formability in a temperature range between 1050 and 1150°C can be anticipated from the results of performed deformation tests making them even more promising as wrought alloys.