The β phase (Al ₁₂Mg ₁₇) precipitated by heat treatment in some alloy compositions may result deterioration of corrosion resistance. However, much of its role remains unclear. The effect of the β phase on the corrosion resistance behavior in a NaCl solution was presented in this study. The specimen was Mg-9mass%Al (AM90) alloy and the content of the β phase precipitant was controlled systematically by aging time at 473 K. Area rate of β and lamellar phase in the specimens were 0, 10 and 100%, respectively. According to the results of cathodic polarization curves measurement, the corrosion current density of α phase was 0.215 A/m2 and β phase of it was 0.096 A/m2. While, the specimen includes 10% of β and lamellar phase showed large corrosion current density of 0.251 A/m2. Positive correlation between the β phase and the open circuit potential, suggest that the β phase acts as a cathodic electrode. Moreover, the microstructure after postentiostatic corrosion tests was also support the role of β phase.

In this study, modification of the AZ91 magnesium alloy surface layer with a CO2 continuous wave operation laser has been taken on. The

extent and character of structural changes generated in the surface layer of the material was being assessed on the basis of both macro- and

microscopy investigations, and the EDX analysis. Considerable changes in the structure of the AZ91 alloy surface layer and the

morphology of phases have been found. The remelting processing was accompanied by a strong refinement of the structure and a more

uniform distribution of individual phases. The conducted investigations showed that the remelting zone dimensions are a result of the

process parameters, and that they can be controlled by an appropriate combination of basic remelting parameters, i.e. the laser power, the

distance from the sample surface, and the scanning rate. The investigations and the obtained results revealed the possibility of an effective

modification of the AZ91 magnesium alloy surface layer in the process of remelting carried out with a CO2 laser beam.

In the manufacturing sector, the processing of magnesium alloys through the liquid casting route is one of the promising methods to manufacture automotive and aircraft components, for their excellent mechanical properties at the lower weight. Investment casting process has the great cabaility to produce near net shape complex castings for automotive and aircraft applications. The distinct and attractive engineering properties of magnesium alloys have shown to be promising in terms of its potential to replace materials such as cast iron, steel, and aluminum In this regard, the efforts to develop processing technology for these alloys for their wide range of applications in industries have been reported by the scientific and engineering community. For successful production of magnesium alloy castings, it requires specialized foundry techniques because of the particular chemical and physical properties of magnesium; especially the reactive and oxidative nature of these alloys. The industry is young enough, to tap the potential.

Magnesium alloys thanks to their high specific strength have an extensive potential of the use in a number of industrial applications. The most important of them is the automobile industry in particular. Here it is possible to use this group of materials for great numbers of parts from elements in the car interior (steering wheels, seats, etc.), through exterior parts (wheels particularly of sporting models), up to driving (engine blocks) and gearbox mechanisms themselves. But the use of these alloys in the engine structure has its limitations as these parts are highly thermally stressed. But the commonly used magnesium alloys show rather fast decrease of strength properties with growing temperature of stressing them. This work is aimed at studying this properties both of alloys commonly used (of the Mg-Al-Zn, Mn type), and of that ones used in industrial manufacture in a limited extent (Mg-Al-Sr). These thermomechanical properties are further on complemented with the microstructure analysis with the aim of checking the metallurgical interventions (an effect of inoculation). From the studied materials the test castings were made from which the test bars for the tensile test were subsequently prepared. This test took place within the temperature range of 20°C – 300°C. Achieved results are summarized in the concluding part of the contribution.

This work presents an influence of cooling rate on crystallization process, structure and mechanical properties of MCMgAl12Zn1 cast magnesium alloy. The experiments were performed using the novel Universal Metallurgical Simulator and Analyzer Platform. The apparatus enabled recording the temperature during refrigerate magnesium alloy with three different cooling rates, i.e. 0.6, 1.2 and 2.4°C/s and calculate a first derivative. Based on first derivative results, nucleation temperature, beginning of nucleation of eutectic and solidus temperature were described. It was fund that the formation temperatures of various thermal parameters, mechanical properties (hardness and ultimate compressive strength) and grain size are shifting with an increasing cooling rate.

In spite of the fact that in most applications, magnesium alloys are intended for operation in environments with room temperature, these

alloys are subject to elevated temperature and oxidizing atmosphere in various stages of preparation (casting, welding, thermal treatment).

At present, the studies focus on development of alloys with magnesium matrix, intended for plastic forming. The paper presents results of

studies on oxidation rate of WE43 and ZRE1 magnesium foundry alloys in dry and humidified atmosphere of N2+1%O2. Measurements of

the oxidation rate were carried out using a Setaram thermobalance in the temperature range of 350-480°C. Corrosion products were

analyzed by SEM-SEI, BSE and EDS. It was found that the oxide layer on the WE43 alloy has a very good resistance to oxidation. The

high protective properties of the layer should be attributed to the presence of yttrium in this alloy. On the other hand, a porous, two-layer

scale with a low adhesion to the substrate forms on the ZRE1 alloy. The increase in the sample mass in dry gas is lower than that in

humidified gas.

In this study, high performance magnesium-yttria nanocomposite’s room temperature, strength and ductility were significantly enhanced by the dispersion of nano-sized nickel particles using powder blending and a microwave sintering process. The strengthening effect of the dispersed nano-sized nickel particles was consistent up to 100°C and then it gradually diminished with further increases in the test temperature. The ductility of the magnesium-yttria nanocomposite remained unaffected by the dispersed nano-sized nickel particles up to 100°C. Impressively, it was enhanced at 150°C and above, leading to the possibility of the near net shape fabrication of the nanocomposite at a significantly low temperature.

Magnesium-based alloys are widely used in the construction, automotive, aviation and medical industries. There are many parameters that can be modified during their synthesis in order to obtain an alloy with the desired microstructure and advantageous properties. Modifications to the chemical composition and parameters of the synthesis process are of key importance. In this work, an Mg-based alloy with a rare-earth element addition was synthesized by means of mechanical alloying (MA). The aim of this work was to study the effect of milling times on the Mg-based alloy with a rare-earth addition on its structure and microhardness. A powder mixture of pure elements was milled in a SPEX 8000D high energy shaker ball mill under an argon atmosphere using a stainless steel container and balls. The sample was mechanically alloyed at the following milling times: 3, 5, 8 and 13 h, with 0.5 h interruptions. The microstructure and hardness of samples were investigated. The Mg-based powder alloy was examined by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and using a Vickers microhardness test. The results showed that microhardness of the sample milled for 13 h was higher than that of those with milling time of 3, 5 and 8 h.

Magnesium-based materials constitute promising alternatives for medical applications, due to their characteristics, such as good mechanical and biological properties. This opens many possibilities for biodegradable materials to be used as less-invasive options for treatment. Degradation is prompted by their chemical composition and microstructure. Both those aspects can be finely adjusted by means of proper manufacturing processes, such as mechanical alloying (MA). Furthermore, MA allows for alloying elements that would normally be really hard to mix due to their very different properties. Magnesium usually needs various alloying elements, which can further increase its characteristics. Alloying magnesium with rare earth elements is considered to greatly improve the aforementioned properties. Due to that fact, erbium was used as one of the alloying elements, alongside zinc and calcium, to obtain an Mg₆₄Zn₃₀Ca₄Er₁ alloy via mechanical alloying. The alloy was milled in the SPEX 8000 Dual Mixer/Mill high energy mill under an argon atmosphere for 8, 13, and 20 hours. It was assessed using X-ray diffraction, energy dispersive spectroscopy and granulometric analysis as well as by studying its hardness. The hardness values reached 232, 250, and 302 HV, respectively, which is closely related to their particle size. Average particle sizes were 15, 16, and 17 μm, respectively

In order to investigate the effect of the milling time on the corrosion resistance of the Mg65Zn30Ca4Pr1 alloy, powders of the alloy were prepared and milled for 13, 20, and 70 hours, respectively. The samples were sintered using spark plasma sintering (SPS) technology at 350◦C and pressure of 50 MPa. The samples were subjected to potentiodynamic immersion tests in Ringer’s solution at 37◦C. The obtained values of Ecorr were –1.36, –1.35, and –1.39 V, with polarization resistance Rp = 144, 189, and 101 Ω for samples milled for 13, 20 and 70 h, respectively. The samples morphology showed cracks and pits, thus signaling pitting corrosion.

The paper presents low-cycle fatigue (LCF) characteristics of selected magnesium alloys used, among others, in the automotive and aviation industries. The material for the research were bars of magnesium alloys AZ31 and WE43 after hot plastic working. Due to their application(s), these alloys should have good/suitable fatigue properties, first of all fatigue durability in a small number of cycles.

Low-cycle fatigue tests were carried out on the MTS-810 machine at room temperature. Low-cycle fatigue trials were conducted for three total strain ranges Δεt of 0.8%, 1.0% and 1.2% with the cycle asymmetry factor R = –1. Based on the results obtained, fatigue life characteristics of materials, cyclic deformation characteristics σa = f(N) and cyclic deformation characteristics of the tested alloys were developed. The tests have shown different behaviors of the tested alloys in the range of low number of cycles. The AZ31 magnesium alloy was characterized by greater fatigue life Nf compared to the WE43 alloy.

AM50/Mg2Si composites containing 5.7 wt. % and 9.9 wt. %. of Mg2Si reinforcing phase were prepared successfully by casting method. The microstructure of the cast AM50/Mg2Si magnesium matrix composites was investigated by light microscopy and X-ray diffractometry (XRD). The microstructure of these composites was characterized by the presence of α-phase (a solid solution of aluminium in magnesium), Mg17Al12 (γ-phase), Al8Mn5 and Mg2Si. It was demonstrated that the Mg2Si phase was formed mainly as primary dendrites and eutectic.

The purpose of this study has been to determine the effect of fertilisation with urea-ammonium nitrate (UAN) solution enriched with P, Mg or S on the content of macronutrients in the grain and straw of maize. The following fertilisers were tested in the field experiment: ammonium nitrate, urea, UAN – 32% N; RSM+S – 26% N + 3% S; RSM+P(Medium) – 26% N and 4.80% P; RSM+P(Starter) – 21% N and 7.86% P; UAN + Mg – 20% N + 4% Mg. In each year of the experiment, significant differentiation in the contents of P, K, Ca, Mg and S in maize grain and straw was observed, depending on the applied nitrogen fertilisation. However, considering the average values from each treatment achieved over the three years, it was demonstrated that the fertilisation significantly changed only the content of P and S in grain and K and Ca in straw of maize. The removal of nutrients was the highest in the second year of the research and amounted in kg∙ha ^–1: P – about 100, K – about 350, Ca – about 80, Mg – about 35 and S – about 31, which in turn were differentiated over the years of the experiment in the three years. The removal of P, K, Mg and S also significantly depended on fertilisation. Significant differences, however, most often concerned the control treatment relative to the fertilised ones. The contribution of grain to the accumulation of nutrients also varied significantly in the three years of the experiment. Significantly the lowest share of grain in terms of P and S accumulation was noted in maize grown without N fertilisation.

The results of some mechanical properties of four Mg-5Al-xRE-0.4Mn (x = 1 – 5) alloys are presented. The microstructure of

experimental alloys consisted of an α-Mg phase and an α+γ semi-divorced eutectic, Al11RE3 phase and an Al10RE2Mn7 intermetallic

compound. For gravity casting in metal mould alloys, Brinell hardness, impact strength, tensile and compression properties at ambient

temperature were determined. The performed mechanical tests allowed the author to determine the proportional influence of the mass

fraction of rare earth elements in the alloys on their tensile strength, yield strength, compression strength and Brinell hardness. The

impact strength of the alloys slightly decreases with a rise in the rare earth elements mass fraction.

The modified surface layers of Mg enriched with Al and Si were fabricated by thermochemical treatment. The substrate material in contact with an Al + 20 wt.% Si powder mixture was heated to 445ºC for 40 or 60 min. The microstructure of the layers was examined by OM and SEM. The chemical composition of the layer and the distribution of elements were determined by energy dispersive X-ray spectroscopy (EDS). The experimental results show that the thickness of the layer is dependent on the heating time. A much thicker layer (1 mm) was obtained when the heating time was 60 min than when it was 40 min (600 μm). Both layers had a non-homogeneous structure. In the area closest to the Mg substrate, a thin zone of a solid solution of Al in Mg was detected. It was followed by a eutectic with Mg17Al12and a solid solution of Al in Mg. The next zone was a eutectic with agglomerates of Mg2Si phase particles; this three-phase structure was the thickest. Finally, the area closest to the surface was characterized by dendrites of the Mg17Al12phase. The microhardness of the modified layer increased to 121-236 HV as compared with 33-35 HV reported for the Mg substrate.

Cast magnesium matrix composites reinforced with silicon carbide particles were investigated by using Raman microscopy. 3C, 4H and 6H polytypes of SiC particles were identified in the investigated composites. Additionally, Mg2Si compound was detected by Raman microscopy in the composites microstructure.

Magnesium alloys are one of the lightest of all the structural materials. Because of their excellent physical and mechanical properties the

alloys have been used more and more often in various branches of industry. They are cast mainly (over 90%) on cold and hot chamber die

casting machines. One of the byproducts of casting processes is process scrap which amounts to about 40 to 60% of the total weight of a

casting. The process scrap incorporates all the elements of gating systems and fault castings. Proper management of the process scrap is

one of the necessities in term of economic and environmental aspects.

Most foundries use the process scrap, which involves adding it to a melting furnace, in a haphazard way, without any control of its content

in the melt. It can lead to many disadvantageous effects, e.g. the formation of a hard buildup at the bottom of the crucible, which in time

makes casting impossible due to the loss of the alloy rheological properties. The research was undertaken to determine the effect of an

addition of the process scrap on the mechanical properties of AZ91 and AM50 alloys. It has been ascertained that the addition of a specific

amount of process scrap to the melt increases the mechanical properties of the elements cast from AZ91 and AM50 alloys.

The increase in the mechanical properties is caused mainly by compounds which can work as nuclei of crystallization and are introduced

into the scrap from lubricants and anti-adhesive agents. Furthermore carbon, which was detected in the process scrap by means of SEM

examination, is a potent grain modifier in Mg alloys [1-3].

The optimal addition of the process scrap to the melt was determined based on the statistical analysis of the results of studies of the effect

of different process scrap additions on the mean grain size and mechanical properties of the cast parts.

Experimental Mg-Al-RE type magnesium alloys for high-pressure die-casting are presented. Alloys based on the commercial AM50

magnesium alloy with 1, 3 and 5 mass % of rare earth elements were fabricated in a foundry and cast in cold chamber die-casting

machines. The obtained experimental casts have good quality surfaces and microstructure consisting of an α(Mg)-phase, Al11RE3,

Al10RE2Mn7 intermetallic compound and small amount of α+γ eutectic and Al2RE phases.

Magnesium alloy with 5 wt% Al, 0.35 wt% Mn and 5 wt% rare earth elements (RE) was prepared and gravity cast into a sand mould.

Microstructure investigations were conducted. Analyses of the Mg-Al-RE alloy microstructure were carried out by light microscopy,

scanning electron microscopy and the XRD technique. In the as-cast condition, the alloy was composed of α-Mg, Al11RE3 and

Al10RE2Mn7 intermetallic phases. Additionally, due to non-equilibrium solidification conditions, an Al2RE intermetallic phase was

revealed.

This work presents the results of the research of the effect of the inoculant Emgesal Flux 5 on the microstructure of the magnesium alloy AZ91. The concentration of the inoculant was increased in samples in the range from 0.1% to 0.6%. The thermal processes were examined with the use of Derivative and Thermal Analysis (DTA). During the examination, the DTA samplers were preheated up to 180 °C. A particular attention was paid to finding the optimum amount of inoculant, which would cause fragmentation of the microstructure. The concentration of each element was verified by means of a spark spectrometer. In addition, the microstructures of the samples were examined with the use of an optical microscope, and an image analysis with a statistical analysis using the NIS–Elements program were carried out. Those analyses aimed at examining the differences between the grain diameters of phase αMg and eutectic αMg+γ(Mg17Al12) in the prepared samples as well as the average size of each type of grain by way of measuring their perimeters. This paper is an introduction to a further research of grain refinement in magnesium alloys, especially AZ91. Another purpose of this research is to achieve better microstructure fragmentation of magnesium alloys without the related changes of the chemical composition, which should improve the mechanical properties.

To the main advantages of magnesium alloys belongs their low density, and just because of such property the alloys are used in aviation and rocket structures, and in all other applications, where mass of products have significant importance for conditions of their operation. To additional advantages of the magnesium alloys belongs good corrosion resistance, par with or even surpassing aluminum alloys. Magnesium is the lightest of all the engineering metals, having a density of 1.74 g/cm3 . It is 35% lighter than aluminum (2.7 g/cm3 ) and over four times lighter than steel (7.86 g/cm3 ). The Mg-Li alloys belong to a light-weight metallic structural materials having mass density of 1.35-1.65 g/cm3 , what means they are two times lighter than aluminum alloys. Such value of mass density means that density of these alloys is comparable with density of plastics used as structural materials, and therefore Mg–Li alloys belong to the lightest of all metal alloys. In the present paper are discussed melting and crystallization processes of ultra-light weight MgLi12,5 alloys recorded with use of ATND methods. Investigated magnesium alloy was produced in Krakow Foundry Research Institute on experimental stand to melting and casting of ultra-light weight alloys. Obtained test results in form of recorded curves from ATND methods have enabled determination of characteristic temperatures of phase transitions of the investigated alloy.

Al- and Al/Zn-enriched layers containing intermetallic phases were deposited on the Mg substrate by heating the Mg specimens in contact with the powdered materials in a vacuum furnace. The Al-enriched surface layers were produced using Al powder, whereas the Al/Znenriched layers were obtained from an 80 wt.% Al + 20 wt.% Zn powder mixture. The microstructure and composition of the layers were analyzed by optical microscopy, scanning electron microscopy and X-ray diffraction. The results showed that the Al-enriched layer comprised an Mg17Al12 intermetallic phase and a solid solution of Al in Mg. The layer obtained from the Al+Zn powder mixture was composed of Mg-Al-Zn intermetalic phases and a solid solution of Al and Zn in Mg. Adding 20% of Zn into the Al powder resulted in the formation of a considerably thicker layer. Moreover, the hardness of the surface layers was much higher than that of the Mg substrate.