Why can the nuclear fuel cladding in a fission reactor cause an explosion in the core? If SiC vaporizes in a gas-turbine environment, why have SiC ceramic matrix composites become standard in aerospace engines? Why do all materials seemingly vaporize in the cold vacuum of very low earth orbit? Why is the precious metal iridium an excellent material for both jewelry and hypersonics? How can cork keep astronauts comfortable during atmospheric re-entry? This course will teach students fundamental material degradation mechanisms that drive materials selection and material failure in extreme environments, such as oxidation, creep, fatigue, embrittlement, interdiffusion, thermal cycling and coefficient of thermal expansion mismatch, stability under fission and fusion irradiation. A thorough understanding of various extreme environments will be gained and used to understand legacy and recent advanced materials selection for a variety of applications, such as industrial and aerospace gas turbines, nuclear fission and fusion reactors, very low earth orbit, hypersonics, and re-entry. Specific material systems to be covered are Ni-base superalloys, oxidation resistant overlay coatings, thermal barrier coatings, SiC ceramic matrix composites, environmental barrier coatings, accident tolerant fuel cladding, atomic oxygen resistant polymers, thermal protection systems, and ultrahigh temperature ceramics.