Question

4. Describe what is meant by a metastable state. Explain why metastable materials can be used in applications - even life safety applications - even though they are by definition not stable. 5. Why does martensite need to be tempered? Describe what happens when you "temper” martensite 6. What is the crystal structure for martensite? Is martensite formation a diffusional or diffusionless process?

Answer 1

metastable state- it particular excited state of atom or nucleus that has longer lifetime than the lowest,often energy state.

Essentially, martensite is a highly suersaturo ed solid solution of carbon in ison, which during tempering rejects Carbon in the form of finely divided carbide phases. The end ressult of tempering is a fine dispersion of Carbides in an d iron matrix which ofter bears little structural similarty to the original as quenched martensite 2 @ Any & fons - Martensite is a body-centered tetragonal form of iron in which some Carbon dissolved. mortensite. The martensite mechanism formation is a non diffusional

martensite- it's tempting is necessary because it is normally brittle.

martensite is a body - centered tetragonal form of iron and martensite formation is non diffusional mechanism.