# Investigation of Phase Equilibrium In Magnesium Alloys through Diffusion Couples

Mechanics

Oct 27, 2013 (4 years and 8 months ago)

107 views

Investigation of Phase Equilibrium In
Magnesium Alloys through Diffusion
Couples

Team H:

Sloan
Dantzler

-

Alan
Dorsinville

-

Vanay

Joynes

-
Lankenau

High School

Washington
-
Bishop
McDevitt

HS

1

Introduction

Purpose

Hypothesis

Mg
-
Ca
-
Zn alloy

Procedure

Diffusion Couple Experiment

Methods

Data

Microstructure

Discussion

Conclusion/Future Work

2

Our goal is to prove Mg, Ca and Zn can be
fused together to create a stable phase under
certain conditions.

What we learned:

Why magnesium alloys are important

Thermodynamics

Gibbs Free Energy

Phase Diagrams

Diffusion Couple Experiment

3

WHY?

Mg alloys are:

Light, Low Density

Strong

4

Improve oxidation resistance

Improve creep resistance

Increase hardness

5

Thermodynamics is the relationship between
heat and the ability for mechanical energy or
work to be done.

6

T (
°
C)

Ice

Water

Vapor

The less free Gibbs
energy a phase has,
the more stable it
is.

G

7

Phase Diagram: Isothermal Section

A graph showing all the phases of a substance under
different conditions

I
t shows us:

All the phases whether
stable,metastable

or unstable.

The number of phases

Each phase’s composition

Carl and Liu (2004)

340

8

The purpose of our experiment is to prove a
magnesium alloy (Ca
2
Mg
5
Zn
13
) at the predicted
circumstances

Our hypothesis is to prove that a stable
magnesium alloy does exist at 340

9

Is the action of putting two materials together
in close contact so they may diffuse into each
other

The area of contact, where the diffusion took
place, is where the alloy will form.

MgCa

Alloy

Zn

10

Step 1:Polishing Our Samples

We polished our samples for

smooth surfaces. The better
the polishing, the better the
results.

Mg
-
30% Ca

Zn

11

Step 2:Diffusion Couple

First we put our samples in the clamp.

Then we put them in the furnace at
340

.

12

Step 3:Quenching

13

Step 4:Mounting & Cutting Sample

14

Step 5:Polishing and Etching for
Characterization

15

Step 6: Etch and Examine
16

Results

After nine days at 340 C, only one of our
samples diffused.

Reasons of error

Clamp was not tight enough

Oxidation

17

Diffused Layer

Crack

Defects

200
μ
m

100
μ
m

MgCa

Zn

18

MgCa

Zn

Summary

At the moment, our hypothesis is unjustified

Future Work

Determine and recognize phases/Characterization

Possibly finer polishing or longer time frame

19

Magnesium

Alloy

Diffusion
Couple
Experiment

Thermodynamics

Phase Diagram

Gibbs Free
Energy

20

We would like to thank:

SEEMS Faculty

Dr.
Zi
-
Kui

Liu

Mr.
Sunghoon

Lee

Ms. Jody Markley

Mr. Derek James

Mr. Joshua Harper

UBMS Staff

21