CH1012
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3
METAL ALLOYS I
Alloy = a material with
metallic
properties resulting from the
combination of ³ 2 elements.
properties resulting from the
combination of ³ 2 elements.
Gold 24 carat 100%
14 carat 58% alloy with Ag,Cu
14 carat 58% alloy with Ag,Cu
Brass 67% Cu 33% Zn alloy
1) Solution alloys - homogenous
mixtures,
components dispersed randomly, uniformly.
components dispersed randomly, uniformly.
(a) Substitutional alloy - atoms of the minor
component substitute for atoms in the bulk
structure. Atoms of similar size & chemical bonding tendecies. eg. brass Cu(1.28) / Zn(1.33)
component substitute for atoms in the bulk
structure. Atoms of similar size & chemical bonding tendecies. eg. brass Cu(1.28) / Zn(1.33)
(b) Interstitial alloy - one atom type is much smaller (typ. main group)
and fits into the interstices of the bulk structure. 0.02%C
eg. Fe (1.24) / C(0.71 Å)
eg. Fe (1.24) / C(0.71 Å)
Low
