Microstructural behavior of Copper Alloys

Microstructural Microstructural behavior of Copper behavior of Copper AlloysAlloysEngr 45 Fall-05Engr 45 Fall-05By: Marco RuizBy: Marco Ruiz Justin MatariJustin Matari Jeremy RomanoJeremy Romano

What we did…What we did…

We casted several different combinations We casted several different combinations of copper alloys. of copper alloys.

Our objective is to observe how different Our objective is to observe how different microstructures can effect these alloys.microstructures can effect these alloys.

Like Dissolves LikeLike Dissolves Like

To obtain a fully dissolved solid solution To obtain a fully dissolved solid solution there needs to be some sort of there needs to be some sort of compatible relationship between a solute compatible relationship between a solute and a solvent.and a solvent.

Knowing the structural similarities Knowing the structural similarities between the two elements we are able to between the two elements we are able to predict whether one will dissolve into the predict whether one will dissolve into the other. other.

http://www.newton.dep.anl.gov/askasci/chem03/chem03348.htmhttp://www.newton.dep.anl.gov/askasci/chem03/chem03348.htm

Question?Question?

What happens when you attempt to What happens when you attempt to dissolve two different microstructures?dissolve two different microstructures?

This experiment will demonstrate the This experiment will demonstrate the behaviors of common alloys:behaviors of common alloys: brass, bronze, copper-silver. brass, bronze, copper-silver.

WarningWarning

Metal gets hotMetal gets hot Use appropriate Use appropriate

protectionprotection Well ventilated areaWell ventilated area

CastingCasting

Attempted to cast Attempted to cast alloys into a pure alloys into a pure calcium mold.calcium mold.

FailedFailed

Casting (back up plan)Casting (back up plan)

Alloy combinationsAlloy combinations

 Sample

1Sample

2Sample

3Sample

4Sample

5Sample

6Sample

7

%Cu 100 85 60 85 60 85 7.5

%Ag - 15 40 - - - 92.5

%Zn - - - 15 40 - -

%Sn - - - - - 15 -

Hard Rh  43 Rh 66  Rh 71 Rb 44 *  *  Rh 55

Zero to low alloyZero to low alloy

Copper 925 silverCopper 925 silver Rh 43 Rh 55 Rh 43 Rh 55

Even distribution of grains Even distribution of grains

High Alloy (fcc structure)High Alloy (fcc structure)

60 Cu-Ag 40 85 Cu-Ag 1560 Cu-Ag 40 85 Cu-Ag 15 Rh 71 Rh 66Rh 71 Rh 66

Both are completely soluble no matter what %.Both are completely soluble no matter what %.

Ag-Cu Phase diagramAg-Cu Phase diagram

Sn (fct), Zn (hcp)Sn (fct), Zn (hcp)

85 Cu-Sn 15 85 Cu-Zn 15 85 Cu-Sn 15 85 Cu-Zn 15 Rb ? Rb 44Rb ? Rb 44

Grains act as barricades, non-uniform dist. Grains act as barricades, non-uniform dist. What a difference!!!What a difference!!!

Sn-Cu Phase diagramSn-Cu Phase diagram

Zn-Cu Phase diagramZn-Cu Phase diagram

60 Cu-Sn 4060 Cu-Sn 40

Solubility limit has Solubility limit has been reachedbeen reached

Unlike Unlike microstructuresmicrostructures

Extremely brittleExtremely brittle

60 Cu-Zn 4060 Cu-Zn 40

Not annealedNot annealed Extremely hardExtremely hard Solubility limit has Solubility limit has

not been reachednot been reached

DiscussionDiscussion

Like solvents, not all molten metals are fully Like solvents, not all molten metals are fully miscible with each other.miscible with each other.

http://www.meta-synthesis.com/webbook/38_laing/tetrahedra.htmlhttp://www.meta-synthesis.com/webbook/38_laing/tetrahedra.html

Copper and zinc ions are about the same size, so except for the electric charge, they are pretty much the same so far as the crystal is concerned……

http://du.edu/~jcalvert/phys/zinc.htmhttp://du.edu/~jcalvert/phys/zinc.htm

Copper ions harden silver by the size of the Copper ions harden silver by the size of the atom. Smaller copper ions cause interstituals in atom. Smaller copper ions cause interstituals in the silver. But, they do not harden copper nearly the silver. But, they do not harden copper nearly as much as tin or zinc.as much as tin or zinc.