Magnesium alloy ingots: Chemical and metallographic analyses

Abstract

The quality of a magnesium die casting is likely dependent on the quality of the feed stock ingot material. Therefore, both DaimlerChrysler and General Motors have established quality assurance measures that include analysis of magnesium ingots. These processes include chemical analysis, corrosion testing, fast neutron activation analysis, and metallography. Optical emission spectroscopy, inductively coupled plasma spectroscopy, and gravimetric analysis are several methods for determining the chemical composition of the material. Fast neutron activation analysis, image analysis and energy dispersive X-ray spectroscopy are used to quantify ingot cleanliness. These experimental techniques are described and discussed in this paper, and example case studies are presented for illustration.

Inclusions in magnesium and its alloys: a review

“…The number of 16 N atoms detected directly corresponds to the number of oxygen atoms in the sample. 56,63,64 In glow discharge source techniques, the sample is exposed to an argon plasma which uniformly erodes material from the sample surface. The sputtered atoms are ionised in this plasma and extracted into a mass spectrometer for separation and detection in GD-MS.…”

“…Metallographic analysis can be combined with image analysis to determine the particle size, number of particles, percentage of oxide in the sample, or with scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) to determine the nature of the inclusions and the possible source of melt contamination. 56 However, optical metallography requires multiple steps: sectioning, grinding, polishing and examination. The technique is therefore time consuming and expensive.…”

“…The number of 16 N atoms detected directly corresponds to the number of oxygen atoms in the sample. 56,63,64…”

Evaluation of corrosion resistance of magnesium alloys in radiator coolants

“…In magnesium alloys that contain manganese, manganese can combine with aluminium to form Al-Mn intermetallics in the form of chunks and needles. 22,23 Major differences between the AZ91D and AM50A microstructures were the continuous network of b-Mg 17 Al 12 phase, the extensive presence of eutectic constituents along the grain boundaries and higher Al content in a-Mg matrix in the AZ91D alloy (Fig. 1).…”

The effect of micro-alloying addition of Cr on age hardening of an Mg–Zn alloy

“…The Cr-containing alloy was indeed solutionized at a slightly higher temperature than the binary alloy without the occurrence of melting. However, considering the known issue of the compositional inhomogeneity of magnesium alloys [25] and the Zn content in the alloy (i.e. lower than its maximal solubility in the solid magnesium thus the solidus temperature of the alloy is higher than the eutectic temperature) [23], this may not be very significant.…”