|
macroscopic.
Visible at magnifications to 25x.
macrostructure.
The structure of metals as revealed by macroscopic
examination of the etched surface of a polished specimen.
magnetite.
Naturally occurring magnetic oxide of iron (Fe3O4).
martensite.
A generic term for microstructures formed by
diffusionless phase transformation in which the parent and product phases
have a specific crystallographic relationship. Martensite is
characterized by an acicular pattern in the microstructure in both
ferrous and nonferrous alloys. In alloys where the solute atoms occupy
interstitial positions in the martensitic lattice (such as carbon in iron),
the structure is hard and highly strained; but where the solute atoms
occupy substitutional positions (such as nickel in iron), the martensite is
soft and ductile. The amount of high-temperature phase that transforms to
martensite on cooling depends to a large extent on the lowest temperature
attained, there being a rather distinct beginning temperature (Ms) and a
temperature at which the transformation is essentially complete (Mf).
mechanical
plating.
Plating wherein fine metal powders are peened onto the
work by tumbling or other means.
metal
dusting.
Accelerated deterioration of metals in carbonaceous
gases at elevated temperatures to form a dustlike corrosion product; a
unique form of high temperature corrosion which forms a dust-like corrosion
product and sometimes develops hemispherical pits on a susceptible metal
surface; simultaneous carburization is generally observed.
metal
ion concentration cell
A galvanic cell caused by a difference in metal ion
concentration at two locations on the same metal surface.
metallic
glass.
An alloy having an amorphous or glassy structure. See
also amorphous solid.
metallizing.
(1) The application of an electrically conductive
metallic layer to the surface of nonconductors. (2) The application of
metallic coatings by nonelectrolytic procedures such us spraying of molten
metal and deposition from the vapor phase.
|
|
meteor
perforation
Perforation of material in outer space resulting from
meteor strikes.
microbial
corrosion.
See biological corrosion.
microscopic.
Visible at magnifications above 25x.
microstructure.
The structure of a prepared surface of a metal as
revealed by a microscope at a magnification exceeding 25x.
mill
scale.
The heavy oxide layer formed during hot fabrication or
heat treatment of metals.
mixed
potential.
The potential of a specimen (or specimens in a galvanic
couple) when two or more electrochemical reactions are occurring. Also
called galvanic couple potential.
molal
solution.
Concentration of a solution expressed in moles of
solute divided by 1000 g of solvent.
molar
solution.
Aqueous solution that contains 1 mole (gram-molecular
weight) of solute in 1 L of the solution.
mole.
One mole is the mass numerically equal (in grams) to
the relative molecular mass of a substance. It is the amount of substance
of asystem that contains as many elementary units (6.023 exp23) as
there are atoms of carbon in 0.012 kg of the pure nuclide C12; the
elemenary unit must be specified and may be an atom, molecule, ion,
electron, photon, or even a specified group of such units.
moneypenny-strauss
test.
Corrosion testing in a copper-sulfate solution
containing sulfuric acid. Used to detect the susceptibility of stainless
steel to intergranular corrosion.
monomer.
A molecule usually an organic compound, having the
ability to join with a number of identical molecules to form a polymer.
|