Barrier oxides on high-performance alloys – growth mechanisms and failure modes

Research Project, 2020 – 2024

High temperature materials play a crucial role in the quest for a sustainable society and are indispensable to modern society, enabling many industrial processes. Practically all high temperature materials react spontaneously to form e.g., oxides, carbides, nitrides in their environments. If unhindered, these reactions rapidly destroy the materials. Hence, all such alloys are designed to form barrier oxides, separating the metal from the corrosive environment. The urgent need to increase the energy efficiency of thermal processes implies using higher operating temperatures. This provides a strong driver for developing alloys with better ability to withstand high temperature corrosion. This project deals with the thermal growth of chromia and alumina barrier layers on high-temperature alloys and with the sequence of events that lead to barrier failure. We address the effect of micro-alloying with the so-called reactive elements (RE´s) and investigate the little-known effect of hydrogen on scale growth. To arrive at validated mechanistic insights into complex corrosion processes, we combine state-of-the-art corrosion experiments with extensive microstructural and chemical analyses using state-of-the-art analytical tools on the atomic- nano – and micro-scale. The experimental work is supplemented by First principles modeling (DFT). The ultimate aim is to generate ideas for novel strategies for designing alloys with superior ability to resist high-temperature corrosion.