Metals

Aluminum

Introduction

Classification

Detailed studies of the mechanisms involved in recovery and recrystallisation during heat treatment can be done quantitatively with SEM-based analytical techniques instead of using TEM. QUANTAX EDS , EBSD and ARGUS™ provide a fast and quantitative identification of the chemical elements, microstructural and crystal orientation down to the nanoscale. In addition, it is easy to use, non-destructive and relatively inexpensive. The benefit of a large field of view compare to TEM is also required when inspecting large fraction of samples for surface quality control of aluminum products. Surface quality is important since it can influence the corrosion resistance and adhesive bonding and durability. 

Classification of Small Al Particles

Abrasion in Production Lines Can Be a Source of Contaminated Products and/ or Malfunctioning Machinery

Abrasion in production lines can be a source of contaminated products and/or malfunctioning machinery. Using micro-XRF is straight-forward to classify steel particles with sizes down to 50 µm because their heavy matrix will allow a reliable quantitative analysis of the main elements. For the classification of Aluminum flakes usually heavy elements are of importance, whereas the main element is very light. Therefore, it is difficult to asses the alloy type of thin aluminum particles. The fast mapping capabilities of the M4 TORNADO (PLUS) allow quick scanning of small Al particles and find the thickest part of the sample. This thick region is likely to give the most reliable results for a classification. The region of interest can be cut out from the Hypermap dataset and be quantified for classification.

Map of different Al flakes. The sample is thickest where the color signal is brightest. The left pictrue shows an Al particle of roughly 500 µm width. This particle is folded, whis from the optical image was not apparent. The right pictrue shows an even smaller particle which overall is thicker than the first sample. The thickness information is obtained easiest by a quick Map of the whole particle.
4 different particles with diameters well below 500 µm and much lower thickness where mapped, the thickest part was selected and quantified. The Al sample holder was the piece where the flakes were abraded from. For all particles the heavy elements Pb and Bi are underestimated, because the samples are too thin. Fo the medium elements the quantification still worked for the 2 thicker flakes, but failed for particle 3 and 4. This way to assess the size range for a reliable classification is fast and direct. Aluminum particles that are larger (thicker) than 200 mm can be classified reliably.

Texture

The production of aluminum in the smelter is uniquely controlled by Powder XRD. Hundreds of samples of the hot molten electrolyte are regularly taken, cooled down and analyzed with the D8 ENDEAVOR Aluminum editon. The volume texture of the final metal product can be inspected by XRD.

Microstructural Characterization with XRD

Texture Analysis of Rolled and Drawn Aluminum Sheets

The orientation distribution of grains in a polycrystalline material, commonly referred to as its crystallographic texture, has a profound impact on its mechanical, electrical, and thermal behavior. Commonly, manufacturing processes such as machining, rolling, extruding, and drawing lead to changes in texture which can be measured and controlled to enhance functionality or prevent failure. X-ray Diffraction provides an easy to use non-destructive method for the determination of crystallographic texture.

Process Control

Aluminum Electrolytic Bath Analysis

A major cost factor in Al production is energy for electrolytic smelting of alumina. A melting temperature below 1000 °C is obtained by adding cryolite (Na3CaAlF6), AlF3 and CaF2 to the alumina. The actual composition of such a bath is represented in the mineralogy of the solid cooled electrolyte. This contains chiolite and two forms of Ca-cryolite mixed crystals in addition to the feed material. The bath acidity (ExAlF3) and other control variables are obtained in DQUANT from single XRD peak analysis and the total Ca content that is simultaneously measured by XRF in the D8 ENDEAVOR.