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Microstructural behavior of Copper Alloys. Engr 45 Fall-05 By: Marco Ruiz Justin Matari Jeremy Romano. What we did…. We casted several different combinations of copper alloys. Our objective is to observe how different microstructures can effect these alloys.
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Microstructural behavior of Copper Alloys Engr 45 Fall-05 By: Marco Ruiz Justin Matari Jeremy Romano
What we did… • We casted several different combinations of copper alloys. • Our objective is to observe how different microstructures can effect these alloys.
Like Dissolves Like • To obtain a fully dissolved solid solution there needs to be some sort of compatible relationship between a solute and a solvent. • Knowing the structural similarities between the two elements we are able to predict whether one will dissolve into the other. http://www.newton.dep.anl.gov/askasci/chem03/chem03348.htm
Question? • What happens when you attempt to dissolve two different microstructures? • This experiment will demonstrate the behaviors of common alloys: brass, bronze, copper-silver.
Warning • Metal gets hot • Use appropriate protection • Well ventilated area
Casting • Attempted to cast alloys into a pure calcium mold. • Failed
Zero to low alloy Copper 925 silver Rh 43 Rh 55 Even distribution of grains
High Alloy (fcc structure) 60 Cu-Ag 40 85 Cu-Ag 15 Rh 71 Rh 66 Both are completely soluble no matter what %.
Sn (fct), Zn (hcp) 85 Cu-Sn 15 85 Cu-Zn 15 Rb ? Rb 44 Grains act as barricades, non-uniform dist. What a difference!!!
60 Cu-Sn 40 • Solubility limit has been reached • Unlike microstructures • Extremely brittle
60 Cu-Zn 40 • Not annealed • Extremely hard • Solubility limit has not been reached
Discussion • Like solvents, not all molten metals are fully miscible with each other. • http://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.htm • Copper ions harden silver by the size of the atom. Smaller copper ions cause interstituals in the silver. But, they do not harden copper nearly as much as tin or zinc.