The effect of sodium contamination on magnesium-lithium base alloys

Frost, P.D.; Jackson, J. Hampden; Loonam, A. C.; Lorig, C. H.

doi:10.1007/bf03399119

Cited by 3 publications

(2 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Results of extensive research programs conducted in this country on magnesium-lithium-base alloys have been published in earlier papers (1)(2)(3)(4). In addition to the work done in this country, investigations on magnesium-lithium alloys were carried out in England (5,6) and in Russia (7).…”

mentioning

confidence: 99%

Results of Some Marine-Atmosphere Corrosion Tests on Magnesium-Lithium Alloys

Frost

Fink

Pray

et al. 1955

J. Electrochem. Soc.

View full text Add to dashboard Cite

Magnesium-lithium binary alloys which contain just enough lithium (about 11 wt %) to produce a single-phase, body-centered cubic structure have shown surprisingly good resistance to corrosion in 3% salt solution, ttigh-strength alloys having about 9% lithium and various quantities of aluminum, zinc, and other elements have a mixed hexagonal-plus-body-centered cubic structure. Such alloys generally have poorer corrosion resistance than the single-phase binaries. Three of the high-strength alloys were exposed for 32 months to the sea-coast atmosphere near Daytona Beach, Florida. For comparison purposes, samples of commereial AZ31A-tI24 alloy were exposed at the same time. All alloys were in the form of 4 X 6 X 0.064 in. panels. The AZ31A sheet had corrosion resistance only slightly superior to that of an alloy containing Mg-8.7% Li-5% AI-8~o Zn. The other two alloys, Mg-8.8% Li-7% A1-0.05% Sn-l% Mn and Mg-8.8~ Li-7% Al-l% Sn, had much poorer corrosion resistance.

show abstract

mentioning

confidence: 99%

Results of Some Marine-Atmosphere Corrosion Tests on Magnesium-Lithium Alloys

Frost

Fink

Pray

et al. 1955

J. Electrochem. Soc.

View full text Add to dashboard Cite

show abstract

“…A complication of the use of fluxes seems to be sodium contamination of the melt [35], which decreases the ductility of the alloy. To avoid this problem the quantity of flux used needs to be 35% of the weight charge except when very large quantities of a charge are prepared.…”

Section: Mg-li Alloysmentioning

confidence: 99%

Melting, Alloying and Refining

Magnesium Technology

View full text Add to dashboard Cite

With the automotive, electronic and consumer goods industries embracing magnesium in their applications, magnesium alloys that do not contain zirconium have gained a higher market share than alloys which do. The zirconium-free alloys include important alloy classes such as Mg-Al, Mg-Al-Zn, Mg-Al-Si, Mg-Al-(Rare-Earths), Mg-Al-(Alkaline Earths), Mg-Li and alloys that contain a number of rare alloying elements such as combinations of rare earths, alkaline earths and lanthanides. While Mg-Al, Mg-Al-Zn and Mg-Al-Si are commercial, the other alloy systems are either semi-commercial or being developed. Mg-Al, Mg-Al-Zn, and Mg-Al-Si AlloysThe main alloying elements in these alloys are two or more of the elements from the following list: Al, Zn, Mn, Be, Si.Addition of Al, Zn, and Si are straightforward [1] while Mn and Be require more control. Magnesium can be melted and alloyed to produce Mg-Al based alloys using electric resistance, gas-fired and induction furnaces with mild steel crucibles.As in all magnesium alloys, Mg-Al based alloy melts must be protected against oxidation and burning during melting, alloying and casting. The Mg-Al alloy-melt forms a porous MgO-Al 2 O 3 surface layer, which does not offer resistance to oxidation and burning. Fluxes (employing molten salt mixtures) or fluxless-melting techniques (using protective gas mixtures, such as SO 2 , or SF 6 mixed with CO 2 , dry air or N 2 ) can be used depending on alloy compositions and processing conditions. Flux Melting and RefiningFlux melting, alloying and refining of Mg-Al based alloys has had a long historical development. This can be found in detail in Emley's classic book on magnesium technology [1, pp. 72-73]. Early fluxes consisted of MgCl 2 , which would solidify above the melting point of Mg. This led to chloride inclusions in the melt (Fig. 4.1).In order to solve these problems a number of methods were developed. Flux compositions were usually adjusted to melt below the melting point of the alloys CHAPTER 1 so that they spread-out and protect the solid metal from oxidation prior to melting. Alkaline earth metal chlorides such as BaCl 2 were added to adjust the melting point.Another early method involved the addition of porous substances such as MgO to absorb the chlorides. These techniques did not provide the optimum solution but added to the overall knowledge base on flux melting of Mg.BaCl 2 was also commonly part of the composition of early fluxes due to its high density, which would encourage the flux and the flux-oxide particulates to settle to the bottom. The elimination of BaCl 2 due to environmental regulations prompted wider use of inspissated (thick) flux to promote separation by agglomeration due to the surface tension or tacky character of the salt phase. Between 1922 and 1938, the development of thickened (inspissated fluxes) consisting of MgCl 2 and thickening agents such as MgO and MgF 2 were developed. The flux could provide a thin viscous protective layer on the melt surface and avoided the risk of chloride inclusions arising...

show abstract