Textbook Problem

The memory metal, nitinol, is an alloy of nickel and titanium. It is called a memory metal because after being deformed, a piece of nitinol wire will return to its original shape. The structure of nitinol consists of a simple cubic array of Ni atoms and an inner penetrating simple cubic array of Ti atoms. In the extended lattice, a Ti atom is found at the center of a cube of Ni atoms; the reverse is also true.

a. Describe the unit cell for nitinol.

b. What is the empirical formula of nitinol?

c. What are the coordination numbers (number of nearest neighbors) of Ni and Ti in nitinol?