AICu ligature, Dnipropetrovsk region.

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Aluminum ligature is an alloy of aluminum and various chemical elements. Their list is very diverse, from widely spread copper (Al-Cu ligature) and silicon (AlSi ligature) to aluminum ligature - Aluminum ligature of rare earth scandium (Al-Sc ligature).
In the technical literature, different designations of brands of ligatures having the same composition are used. For example, AlMn ligature can be written as aluminum-manganese ligature, aluminum-manganese ligature, or as aluminum-manganese ligature.(//tractor-service.com)
Aluminum ligature often has numbers in the brand designation showing the percentage of the auxiliary element, for example: AlCr10 ligature consists of aluminum and chromium (from 9.0% to 11%). In most cases, the aluminum ligature has a composition of three or four significant elements. But sometimes such as Al-Fe-Si-Mn-Cu ligature are used, with five or more components.
Let's dwell on some of the metals that have an aluminum ligature in their composition.
One of the most common in production and the most universal ligature is aluminum ligature AlTi5B1 (altibor), it is also referred to as ligature AlTiB 5/1, or ligature ATB 5-1. It consists of aluminum, titanium (4.5-5.5%) and boron (0.9-1.1%), used to reduce the grain size of aluminum alloys. "