MATSE EXAM 2 QUESTIONS WITH 100% VERIFIED ANSWERS

Given a liquid solution of 70 mol% MgO/ 30 mol% NiO starting at
2800°C, answer the following questions using the phase diagram
provided in the homework handout. Upon cooling, at what temperature
do the first solids appear and what are their compositions?

A. temperature ~2670C; solid is ~87% MgO
B. temperature ~2670C; solid is ~70% MgO
C. temperature ~2500C; solid is ~87% MgO
D. temperature ~2500C; solid is ~70% MgO
A. temperature ~2670C; solid is ~87% MgO
Given a liquid solution of 70 mol% MgO/ 30 mol% NiO starting at
2800°C, answer the following questions using the phase diagram
provided in the homework handout. At 2600°C, what phases are present
and what are their equilibrium compositions?

A. liquid phase with ~80% MgO; solid phase with ~60% MgO
B. liquid phase with ~60% MgO; solid phase with ~80% MgO
C. liquid phase with ~70% MgO; solid phase with ~70% MgO
D. liquid phase with ~110% MgO; solid phase with ~-10% MgO
B. liquid phase with ~60% MgO; solid phase with ~80% MgO
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Given a liquid solution of 70 mol% MgO/ 30 mol% NiO starting at
2800°C, answer the following questions using the phase diagram
provided in the homework handoutHow many degrees of freedom exist
at 2600°C?

A. 0
B. 1
C. 2
D. 3
B. 1

,Given a liquid solution of 70 mol% MgO/ 30 mol% NiO starting at
2800°C, answer the following questions using the phase diagram in the
homework handout. Below what temperature should the entire system
exist as a solid solution?

A. T < 2670C
B. T < 2600C
C. T < 2500C
D. There is no solid solution between NiO and MgO
C. T < 2500C
A ____phase_________ is a chemically and structurally homogeneous
state of matter, and a ____component______ is one of the substances
comprising this state.

True
False
True
Given a mixture of 70 wt % Mg / 30 wt % Al starting at 500°C and the
phase diagram for the Al-Mg system provided in the homework handout,
answer the following question. Upon cooling, at what temperature do the
first solids appear and what is their composition?

A. Temperature ~465C; Solid is ~89% Mg
B. Temperature ~437C; Solid is ~89% Mg
C. Temperature ~465C; Solid is ~70% Mg
D. Temperature ~437C; Solid is ~70% Mg
A. Temperature ~465C; Solid is ~89% Mg
Given a mixture of 70 wt % Mg / 30 wt % Al starting at 500°C and the
phase diagram for the Al-Mg system provided in the homework handout,
answer the following question. At 450°C, describe the phases that are
present at equilibrium in terms of their composition and relative amounts

A. 9.5% liquid phase with ~68% Mg; 90.5% solid phase with ~89% Mg
B. 90.5% liquid phase with ~70% Mg; 9.5% solid phase with ~70% Mg
C. 90.5% liquid phase with ~68% Mg; 9.5% solid phase with ~89% Mg
D. 9.5% liquid phase with ~70% Mg; 90.5% solid phase with ~70% Mg
C. 90.5% liquid phase with ~68% Mg; 9.5% solid phase with ~89% Mg

,Given a mixture of 70 wt % Mg / 30 wt % Al starting at 500°C and the
phase diagram for the Al-Mg system provided in the homework handout,
answer the following question At 400°C, describe the phases that are
present at equilibrium in terms of their composition and relative amounts

A. 65.5% gamma phase with ~60% Mg; 34.5% delta phase with ~89%
Mg
B. 34.5% gamma phase with ~60% Mg; 65.5% delta phase with ~89%
Mg
C. 65.5% gamma phase with ~70% Mg; 34.5% delta phase with ~70%
Mg
D. 34.5% gamma phase with ~70% Mg; 65.5% delta phase with ~70%
Mg
A. 65.5% gamma phase with ~60% Mg; 34.5% delta phase with ~89%
Mg
Referring to the same Al-Mg diagram provided in the homework
handout, but assuming a 10 wt% Mg liquid solution at 650°C, answer the
following question. Upon cooling, at what temperature do the first solids
appear and what is their composition?

A. temperature ~600C; solid with ~4% Mg
B. temperature ~520C; solid with ~4% Mg
C. temperature ~600C; solid with ~10% Mg
D. temperature ~520C; solid with ~10% Mg
A. temperature ~600C; solid with ~4% Mg
Referring to the same Al-Mg diagram provided in the homework
handout, but assuming a 10 wt% Mg liquid solution at 650°C, answer the
following question. At 450°C, describe the phases that are present at
equilibrium in terms of their composition and relative amounts

A. only alpha phase with 10% Mg
B. only alpha phase with 17.1% Mg
C. 17.1% alpha phase with 10% Mg; 36.1% beta phase with 10%Mg
D. 17.1% alpha phase with 10% Mg; 35.6% beta phase with 10%Mg
A. only alpha phase with 10% Mg
Referring to the same Al-Mg diagram provided in the homework
handout, but assuming a 10 wt% Mg liquid solution at 650°C, answer the
following question. At 300°C, determine the phases that are present at

, equilibrium in terms of their composition and relative amounts

A. only alpha phase with 10%Mg
B. 89.7% alpha phase with ~7% Mg; 10.3% beta phase with ~36% Mg
C. 10.3% alpha phase with ~7% Mg; 89.7% beta phase with ~36% Mg
D. 89.7% alpha phase with ~10% Mg; 10.3% beta phase with ~10% Mg
B. 89.7% alpha phase with ~7% Mg; 10.3% beta phase with ~36% Mg
Referring to the same Al-Mg diagram provided in the homework
handout, at 50% Mg the mixture will melt incongruently at 455C. True or
False

True
False
False
Referring to the same Al-Mg diagram, when the peritectic reaction that
occurs when a 36.1 wt% Mg solid (beta-phase per this diagram) is
heated above 450°C it will melt incongruently to form a liquid plus
gamma phase. True or False?

True
False
True
Referring to the same Al-Mg diagram provided in the homework
handout, the stoichiomety of the intermetallic compound corresponding
to the gamma phase that is stable at 100°C is Mg2Al3. True or False?

True
False
False
Referring to the same Al-Mg diagram provided in the homework
handout, according to the phase rule, for a 80 wt % Mg mixture, at a
temperature of 600°C 2 degrees of freedom exist, at 500°C 1 degree of
freedom exists, at 437°C 0 degree of freedom exists, and 300°C 1
degree of freedom exists. True or False?

True
False
True