e88mtm - Engineering 45 The Structure and Properties of...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Engineering 45 The Structure and Properties of Materials Midterm Examination October 26, 1988 Problem 1: The element A crystallizes in the diamond cubic structure. (a) Give the positions of the atoms in the unit cell. (b) Show that each atom in the diamond cubic structure has four nearest neighbors. (c) All elements that crystallize in the diamond cubic structure are either semicon- ductors or insulators. Why are they one or the other and why can they be either? (d) If A is cooled very quickly it forms an amorphous structure. Would you expect it to be a semiconductor, insulator or metal? Problem 2: The element B is a substitutional solute in the polygranular solid A. (a) Plot the expected variation of the diffusivity of B as a function of temperature. Explain the shape of the curve in terms of the mechanisms of diffusion. (b) Assume that a sample of the solution is held at a relatively high temperature and then quenched to room temperature. Plot the expected variation of the diffusivity of
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/05/2011 for the course ENGIN 45 taught by Professor Devine during the Spring '07 term at University of California, Berkeley.

Page1 / 2

e88mtm - Engineering 45 The Structure and Properties of...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online