Microstructures
by George Langford, Sc.D., Massachusetts Institute of Technology, Cambridge, MA, 1966
Copyright©2005 by George Langford
Non Ferrous Alloys - Lesson 1 - Sixth specimen, Part I
This is Muntz metal, a
brass with 40% zinc,
shown at 200X at left. It
has been air cooled from
the all-beta region at
825C. Note the
pronounced
Widmanstaetten alpha.
How would a quenched
specimen differ from
this ?
What about a slowly
cooled specimen ?
The alpha precipitates
inside the beta grains
and on the beta grain
boundaries. The alpha
appears as long, fat
needles in a beta matrix.
There would be much
less alpha (if any) if this
specimen had been
quenched, and more and
"rounder" precipitates if
slowly cooled (i.e., closer
to the equilibrium
structure).
Pause and think a while
before looking at the
next page.