It has better hardness. Fatigue is wear or breakage which results from continuous or frequent use, so the students should think of things which get used often. Door hinges, airplane wings, diving boards, wheel axles, joy sticks on video games are some examples of items which need to resist fatigue. If you don't want to get burned, the handle should be made out of some type of insulating material. The pan, on the other hand, should conduct heat evenly so you can cook your food.
Many metals corrode in reaction to the oxygen in the air.
This is a process known as oxidation or more commonly as rusting.