Due to the combination of high corrosion resistance and suitable mechanical properties, AISI 316L stainless steel is extensively used as the biomaterial for surgical implants. However, heat exposure in inappropriate temperatures can cause its sensitization accompanied by chromium depletion along the grain boundaries. This study deals with an assessment of the susceptibility of sensitized AISI 316L biomaterial to pitting under conditions simulating the internal environment of the human body (Hank’s balanced salt solution, 37 ± 0.5 °C). The resistance to pitting corrosion is tested by the potentiodynamic polarization and by the 50-day exposure immersion test. Corrosion damage after the exposure immersion test is evaluated in the specimens’ cross-sections by optical microscope and SEM. Despite passive behavior in potentiodynamic polarization and shallow, slight corrosion damage observed after exposure, the sensitized AISI 316L biomaterial could represent a risk, especially in long-term implantation even after the chemical removal of high-temperature oxides.

Production of primary aluminium is energetically enormously expensive. The use of secondary (recycled) aluminium, has therefore a high potential to save money and energy while reducing the negative environmental impact of aluminium production. Although the properties of secondary aluminium alloys are generally comparable to those of primary aluminium alloys, the increased Fe content can lead to a significant reduction in the corrosion resistance of these alloys. Secondary (recycled) AlSi7Mg0.3 cast alloy with different iron contents (0.123, 0.454, 0.679 and 1.209 wt. %) in the as-cast and after heat treatment (T6) condition was investigated. The quantitative analysis was focused on the evaluation of the Fe-phases, especially the needle-like Al 5 FeSi phase. The corrosion resistance was measured by a rapid corrosion test (AUDI test). The corrosion damage of the surface was observed macroscopically. The results show that Fe content higher than 0.454 % has no significant effect on the amount and size of needle-like phases of Al 5 FeSi. The corrosion resistance is mainly influenced by the size and length of the Al 5 FeSi phases. Increased Fe content decreases the corrosion resistance of AlSi7Mg0.3 alloy and accelerates the initiation of corrosion.

The article is focused on the analysis of the structure and fracture surface of aluminum alloy specimens. Aluminum alloy AlMg9 was mainly used as an experimental material. The material from which specimens were made was supplied as cast without heat treatment, and specifically the material was produced by the continuous casting method. The structure of the test material was examined using a Neophot 32 optical microscope, and the fracture surface of the test specimen was examined using a scanning electron microscope (SEM). The fatigue life of the aluminum alloy was tested by method of a three-point bending cyclic loading using the parameters-frequency f = 100 Hz, temperature T = 22 ± 5 ℃ and stress ratio R = 0.11. The analysis showed that cast aluminum alloys are very sensitive to casting defects, such as porosity or the content and distribution of intermetallic phases. If large pores or phases are present on or near the surface of the sample, this can be the dominant cause of fatigue crack initiation and reduction of the fatigue lifetime.

Al has very good corrosion resistance and corrosion properties. The corrosion resistance of Al-cast alloys is different because these alloys contain a lot of elements, especially in secondary alloys, which contain more impurity elements, of which Fe is the most common. This study deals with secondary AlSi7Mg0.3 cast alloys, which contain more Fe and are affected by a chloride corrosive environment. This environment was selected based on the application of castings in the automotive industry. The main object was to research the effect of such an environment on basic mechanical properties and fatigue properties. The results show that a higher Fe content does not lead to a significant reduction in the properties of the casting, and the chloride environment is not so harmful. Therefore, it can be stated that the investigated secondary sand-cast experimental materials can replace primary alloys without losing the required corrosion and mechanical properties.

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