Metallurgical Analysis, Microscopy, and Diffraction Vocabulary

Flashcards for review of metallurgical analysis, electron microscopy, and X-ray diffraction, focusing on vocabulary and key concepts.

Density

Measure of the mass per unit volume of a substance, based on the mass, size, and arrangement of the atoms. It is a characteristic property of a substance.

Elemental Analysis

A metallurgical testing tool used to determine all present elements and/or compounds in a given system, emphasizing rapidity and accuracy.

Complete Chemical Analysis

A chemical analysis including those elements in very small proportions. Multiple measurements should not differ by ±0.1% for reliable results.

Selective Chemical Analysis

Separation of one or more minerals in a mixture using the selectivity of chemical agents, either by attacking a single mineral or destroying all except one.

Instrumental Methods (in Elemental Analysis)

Use of modern instruments to expose and isolate certain characteristics of elements, including Emission Spectrograph, X-ray Fluorescence, and Atomic Absorption.

Atomic Absorption

Measuring the absorption of light by atoms, related to the concentration of atoms present, as expressed in Beer-Lambert’s Law.

AAS (or FAAS)

Flame Atomic Absorption Spectrophotometry, requiring the absorption of radiant energy (light) by a neutral atom in a gaseous state.

Acid Digestion

A preliminary step in AAS where geological samples are reduced to solutions using acid attack to eliminate matrix interference by the solid mineral.

Electron Microscopy

Science of imaging specimens on a very fine scale using an electron beam to obtain information on material topography, morphology, composition, and crystallographic information.

Resolution (in Microscopy)

Describes the detail an image holds, quantifying how close lines can be to each other and still be visibly resolved.

Magnetic Lenses

Components consisting of a coil of copper wires inside iron pole pieces, used to converge beams of charged particles and form images by increasing magnetic field.

Transmission Electron Microscope (TEM)

An electron microscope that uses a focused beam of electrons to 'see through' the specimen, producing a 2-D image with high magnification.

Scanning Electron Microscope (SEM)

Microscope that produces images by detecting secondary electrons emitted from the surface due to excitation by the primary electron beam, creating 3-D images.

Energy Dispersive X-Ray (EDX)

Technique used to determine the presence and amounts of substances under SEM by analyzing X-ray dispersions acting as 'signatures' for different materials.

Ion Sputtering

Depositing an ultra-thin coating of electrically-conducting material to prevent the accumulation of static electric fields at the specimen during imaging.

X-ray Diffraction (XRD)

The chief tool for investigating the atomic or crystal structure of minerals with the use of X-rays.

Diffraction

The result of constructive interference of the scattered wavelengths from the periodically arranged scattering centers.

Crystals

Consist of planes of atoms that are spaced a distance d apart and can be resolved into many atomic planes, each with a different d spacing.

Bragg Equation

Explains why the cleavage faces of crystals appear to reflect X-ray beams at certain angles of incidence, providing direct evidence for the periodic atomic structure of crystals.