Micrograph Gallery – Vander Voort

Melted Zirconium

Extensive mechanical twinning was observed in high-purity, electron-beam melted zirconium after hot working and cold drawing. Viewed in polarized light. Magnification bar is 100 μm long.

Wrought pure hafnium

Microstructure of wrought pure hafnium, with an as-polished specimen viewed in polarized light plus sensitive tint, revealing an equiaxed alpha HCP grain structure. A few mechanical twins can be seen at the surface (yellow arrows). The magnification bar is 100 μm long.

As-cast cadmium Bi

Microstructure of Cd - 20% Bi in the as-cast condition, unetched, viewed with polarized light (slightly off the crossed position) plus sensitive tint revealing cadmium dendrites of various orientation. The interdendritic constituent is a eutectic of Cd and Bi, but is too fine to resolve at this magnification. The magnification bar is 200 μm long.

CP Ti AST F 67

Microstructure of CP Ti, ASTM F 67, Grade 2 (specimen in the as-rolled condition) prepared using the three-step method, followed by a vibratory polish, and viewed with crossed polarized light to reveal the grain structure. Note the deformation twins (arrows).

As-cast pure ruthenium

Microstructure of as-cast pure ruthenium, as polished, viewed in polarized light plus sensitive tint revealing a mixture of equiaxed and columnar HCP grains and some small shrinkage cavities (black). The magnification bar is 200 μm long.

Austempered ductile iron

Microstructure of spheroidal graphite in austempered ductile iron, as polished, viewed in polarized light plus sensitive tint revealing the growth pattern of the nodules. The magnification bar is 20 μm long.

Austempered ductile iron

Microstructure of austempered ductile iron tint etched with Beraha’s CdS reagent containing large graphite nodules (arrow), bainite (blue and brown) and retained austenite (white) when viewed with polarized light plus sensitive tint. Original at 500X.

MgB2 fibers

Composite of MgB2 fibers in a polymer binder, as polished and viewed with polarized and a sensitive tint filter (100x, left; 200x, right).9-reinforced-polysulfone

Reinforced polysulfone

Microstructure of a graphite-fabric reinforced polysulfone composite viewed with cross polarized light plus sensitive tint. The magnification bar is 100 μm long.

Low carbon martensite

Low-carbon martensite formed on the polished surface of Temperature Compensator “30” alloy, type 2 (Fe - 0.12% C - 0.6% Mn - 0.25% Si - 30% Ni) after refrigeration in liquid nitrogen. This converted any unstable austenite to martensite with its characteristic shear reaction, visible on a prepared free surface using Nomarski DIC (not etched). Magnification bar is 25 μm in length.

Low carbon martensite

Low-carbon martensite formed on the polished surface of Temperature Compensator “30” alloy, type 2 (Fe - 0.12% C - 0.6% Mn - 0.25% Si - 30% Ni) after refrigeration in liquid nitrogen. The low temperature converted any unstable austenite to martensite with its characteristic shear reaction, visible on a prepared free surface using Nomarski DIC (not etched).

Butterfly martensite

Example of “butterfly” martensite (low carbon martensite) formed on the polished surface of a specimen of High-Expansion 22-3 (Fe - 0.1% C - 0.5% Mn - 0.2% Si - 3.1% Cr - 22% Ni) alloy steel when cooled to -73°C. Unstable austenite transformed to martensite with its characteristic shear which is visible on a free surface using Nomarski DIC ( not etched).

Cu 26% per Zn 5% per Al

β1 martensite formed in fcc alpha phase in a Cu - 26% Zn - 5% Al shape memory alloy (un-etched, polarized light).

Cu 26% per Zn 5% per Al

β1 martensite formed in fcc alpha phase in a Cu - 26% Zn - 5% Al shape memory alloy (un-etched, polarized light).

Spangold

Microstructure of Spangold, Au - 19% Cu - 5% Al, a new jewelry alloy using martensite formation to create a rippled effect (“spangles”) on the surface. The specimen was polished, heated to 100°C for 2 minutes, and quenched in water to form martensite, which produces shear at the free surface. This roughness can be seen using Nomarski DIC without etching. The criss-crossed pattern is produced by forming martensite, polishing and then forming new martensite.