Investigation of Phase Equilibrium In Magnesium Alloys through Diffusion Couples Team H: Sloan Dantzler -Reading High School Alan Dorsinville -Reading.

Investigation of Phase Equilibrium In Magnesium Alloys through Diffusion Couples

Team H:Sloan Dantzler -Reading High SchoolAlan Dorsinville -Reading High SchoolVanay Joynes -Lankenau High School

Khadija Washington -Bishop McDevitt HS

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• Introduction– Purpose– Hypothesis– Mg-Ca-Zn alloy

• Procedure– Diffusion Couple Experiment– Methods

• Data– Microstructure – Discussion

• Conclusion/Future Work

Outline

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• 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

Introduction

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WHY?• Mg alloys are:– Light, Low Density– Strong

Magnesium Alloys

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• Calcium addition– Improve oxidation resistance – Improve creep resistance

• Zinc addition– Increase hardness

Contributed Properties

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

Thermodynamics

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T (°C)

Ice

Water

Vapor

Gibbs Free Energy

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

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Phase Diagram: Isothermal Section

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

• It shows us:– All the phases whether stable,metastable or unstable.– The number of phases – Each phase’s composition

Carl and Liu (2004)

340 ℃

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Purpose

Hypothesis

The purpose of our experiment is to prove a magnesium alloy (Ca2Mg5Zn13) at the predicted circumstances

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

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• 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.

DIFFUSION COUPLE EXPERIMENT

MgCa Alloy Zn

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Step 1:Polishing Our Samples

We polished our samples for smooth surfaces. The better the polishing, the better the results.

Mg-30% Ca

Zn

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Step 2:Diffusion Couple

First we put our samples in the clamp. Then we put them in the furnace at 340 .℃

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Step 3:Quenching

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Step 4:Mounting & Cutting Sample

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Step 5:Polishing and Etching for Characterization

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Step 6: Etch and Examine

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Results

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

• Reasons of error– Clamp was not tight enough– Oxidation

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MicroscopeResults

Diffused Layer

Crack

Defects

200 μm

100 μm

MgCa

Zn

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MgCa

Zn

Summary

• At the moment, our hypothesis is unjustified

• Future Work– Determine and recognize phases/Characterization– Possibly finer polishing or longer time frame

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MagnesiumAlloy

Diffusion Couple

Experiment

ThermodynamicsPhase Diagram

Gibbs Free Energy

What We Learned

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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

Acknowledgements

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Thank You

Any Questions?