material science

material science - diagram for this system and label each...

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Assignment 3 Due date: April 1, 2011 Question 1 One crystalline form of silica (SiO 2 ) has a cubic unit cell, and from X-ray diffraction data it is known that the cell edge length is 0.700 nm. If the measured density is 2.32 g/cm 3 , how many Si 4+ and O 2− ions are there per unit cell? Question 2 The zinc blende crystal structure is one that may be generated from close-packed planes of anions. (a) Will the stacking sequence for this structure be FCC or HCP? Why? (b) Will cations fill tetrahedral or octahedral positions? Why? What fraction of the positions will be occupied? Question 3 Gallium arsenide (GaAs) and indium arsenide (InAs) both have the zinc blende crystal structure and are soluble in each other at all concentrations. Determine the concentration in weight percent of InAs that must be added to GaAs to yield a unit cell edge length of 0.5820 nm. The densities of GaAs and InAs are 5.316 and 5.668 g/cm 3 , respectively. Question 4 Given here are the solidus and liquidus temperatures for the copper–gold system. Construct the phase
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Unformatted text preview: diagram for this system and label each region. Composition ( wt % Au ) Solidus Temperature ( C ) Liquidus Temperature ( C ) 1085 1085 20 1019 1042 40 972 996 60 934 946 80 911 911 90 928 942 95 974 984 100 1064 1064 Question 5 A leadtin alloy of composition 30 wt% Sn70 wt% Pb is slowly heated from a temperature of 150C (300F). (a) At what temperature does the first liquid phase form? (b) What is the composition of this liquid phase? (c) At what temperature does complete melting of the alloy occur? (d) What is the composition of the last solid remaining prior to complete melting? Question 6 A 50 wt% Ni50 wt% Cu alloy is slowly cooled from 1400C (2550F) to 1200C (2190F). 1. At what temperature does the first solid phase form? 2. What is the composition of this solid phase? 3. At what temperature does the liquid solidify? 4. What is the composition of this last remaining liquid phase? 5. 1....
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This note was uploaded on 03/31/2011 for the course ENGR 200 taught by Professor Bougherara during the Spring '11 term at Ryerson.

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material science - diagram for this system and label each...

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