Mg alloys have mechanical properties similar to those of human bones, and have been studied extensively because of their potential use in biodegradable medical implants. In this study, the influence of different heat treatment regimens on the microstructure and mechanical and corrosion properties of biodegradable Mg–Zn–Ga alloys was investigated, because Ga is effective in the treatment of disorders associated with accelerated bone loss. Solid–solution heat treatment (SSHT) enhanced the mechanical properties of these alloys, and a low corrosion rate in Hanks’ solution was achieved because of the decrease in the cathodic-phase content after SSHT. Thus, the Mg–4 wt.% Zn–4 wt.% Ga–0.5 wt.% Y alloy after 18 h of SSHT at 350 °C (ultimate tensile strength: 207 MPa; yield strength: 97 MPa; elongation at fracture: 7.5%; corrosion rate: 0.27 mm/year) was recommended for low-loaded orthopedic implants.

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Nowadays, aluminum alloys with silicon are the most widespread construction materials. To increase the mechanical properties of aluminum alloys, modifying by Sr, Ti, and B are used. However, in the foundries, when using scrap and secondary aluminum alloys, the modifying elements are accumulated in alloys in the form of intermetallic particles that decrease castability. This is because of the modifiers have a short time effect and are not activated when remelting. Hence it is necessary to add the modifiers without reference to intermetallic particles that are exactly presented in the melt. This work investigated the effect of Sr, Ti, and B additions on A356.2 aluminum alloy fluidity obtained by vacuum fluidity test. It was shown that when AlSr10 and AlTi5B1 commercial master alloys are used (up to 0.3 wt.% Sr and 0.5 wt.%Ti), no fluidity decrease is observed. However, adding the same quantity of Ti with the homemade AlTi4 master alloy leads to a considerable fluidity decrease. With the help of scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), the microstructure and phase composition of master alloys and A356.2 alloy after the addition of mentioned master alloys were investigated. Additionally, Thermo- Calc software evaluated the influence of modifier additions on alloy phase composition and phase transition temperatures. It was established that the influence of the modifier additions on the fluidity of the A356.2 alloy is connected with the shape and size of crystals that contained modifier elements in the structure of the master alloy. When the coarse crystals of that phases are present, these crystals’ incomplete dissolution is possible, inhibiting the free melt flow.