advanced materials refers to the materials which are used in special applications for example CoCr alloys, Stainless steels and Ti alloys are used as biomaterials, superalloys, high temperature alloys, shape memory alloys etc
there are certain conditions that needs to be fulfilled for a specific reaction to occur. for example for titanium and hydrogen the start of reaction takes place at 300 C. and for the reaction to occur the there must be a contact between the metals in your case. and it will be diffusion...
yield strength and tensile strength are different.
there is no such formula to calculate the yield stress.
yield stress can be obtained from stress strain curve.
usually yield strength is taken at strain offset of 0.002.
i hope it will be helpful to u
good luck :)