7. Ductile fracture in a tensile-test sample is also called.

a) cup-and-cone fracture b) transgranular fracture c) intergranular fracture d) cleavage

8. Which of the following is NOT right for rare-earth metals?

a) Rare-earth metals are generally difficult to mine and process, and hence are available in small quantities.

b) Rare-earth metals are less common in earth's crust than precious metals such as gold and platinum.

c) Rare-earth metals have unique magnetic and electrical properties, and are essential in many modern technologies.

d) The widely used rare-earth metals include yttrium, lanthanum, cerium, samarium, neodymium, etc.

7. a) cup-and-cone fracture, all are right.

Explanation:

Ductility is the ability of the ability to undergoing significant plastic deformation before the rapture. An example of the cup and cone fracture can show this, which is a type of failure observed in ductile metals. Being subjected to uniaxial force it is essential to separate the body into pieces as the application of intense tensile stress. As ductility and malleability are all ways correlated thee material properties depend on the temperature of the metal. Rare earth metal is not commonly found in places and the chemical composition also varies as these are diverse and are used by people in everyday device some smartphones also consist of these elements.