In this study, graphene nanoplatelets (GNPs) and boron carbide (B4C) nano reinforcements were incorporated to the pure magnesium (Mg). Powder metallurgy route was used to fabricate composite samples. Microstructures of specimens were examined and tensile, hardness, wear tests were performed to determine the mechanical and tribological performance of produced samples. The results indicate that the hardness was increased especially with the addition of 2% B4C and 0.5% GNPs reinforcements. A general trend was observed for the enhancements of yield and tensile strengths when nano reinforcements were added to the pure magnesium. The composite samples showed better wear resistance than the unreinforced sample. However, thermal conductivity began to decrease with the addition of B4C reinforcements. It is also observed that the porosity level was also higher for the composite samples.

The present study aims to produce graphene nanoplatelet-coated B4C ceramic particle using semi-powder method and to investigate the effect of graphene nanoplatelets on wear and corrosion performance of Al–Si-based metal matrix hybrid composites. For this purpose, first graphene nanoplatelets at different ratios (0.25, 0.5, and 1 vol.%) were coated to the surfaces of B4C particles and then the Al–Si alloy was infiltrated into the reinforcements by gas pressure infiltration method. The characterization of graphene nanoplatelet-coated B4C powders and its composites was carried out by X-ray diffraction, differential scanning calorimetry, scanning electron microscope, and transmission electron microscope analysis. Tribological properties were investigated by reciprocating ball-on-flat method under three different loads (10–20–40 N) in a dry environment. The corrosion resistance was carried out with Tafel polarization method in 3.5% NaCl solution. Characterization results show that graphene coated on the B4C surface was successfully achieved by semi-powder method. After infiltration process, a new phase formation was not observed, but porosity increased with the increase of graphene content. When the boron carbide surface was coated with 0.5vol.% graphene, it was determined that the specific wear resistance increased by 55% and the corrosion resistance decreased by 12%.

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The purpose of this study is to analyse the microstructure and corrosion properties of homogenised and aged AA 6063 aluminium alloys, containing up to 2% Ti, after the conventional casting technique. The microstructure of the homogenised and aged alloys was examined using an optic microscope, and scanning electron microscope. The micro-hardness test was used for the hardness measurements of the investigated alloys. Corrosion tests were performed by suspending samples of certain sizes into 30 gr/l NaCl + 10 ml/l HCl solutions, measuring the mass loss; potentiodynamic polarisation measurements were carried out in the same solution. The microstructure characterization of the investigated alloys shows the Al (matrix), non-shaped dark globular grey-coloured phase and rod-shaped phases formed at the grain boundaries. The non-shaped dark grey-coloured phase is Mg 2 Si. The rod-shaped phase, formed in the microstructure of the Ti-added AA 6063 alloys, is Al 3 Ti. The Ti content of the alloy increases, the Al 3 Ti phase tends to elongate and become plated. The results of the corrosion tests proved that the corrosion rate decreased in alloys containing less than 1% Ti, and the rate of corrosion increased in alloys containing more than 1% Ti, regardless of whether the alloys were homogenised and aged. Another observation was that aging heat treatment improved corrosion resistance.Keywords: non ferrous metals and alloys, casting, corrosion, micro structure Celem niniejszej pracy jest analiza mikrostruktury i właściwości korozyjnych poddanych obróbce cieplnej stopów aluminium AA 6063, zawierających do 2% Ti, po odlewaniu konwencjonalnym. Mikrostrukturę homogenizowanych stopów zbadano za pomocą mikroskopii optycznej i skaningowej mikroskopii elektronowej. Test mikrotwardości zastosowano do pomiaru twardości badanych stopów. Badania korozyjne przeprowadzono poprzez zawieszenie próbki o określonych rozmiarach w roztworze 30 gr/l NaCl + 10 ml/l HCl i pomiar ubytku masy; pomiary potencjo-dynamicznej polaryzacji zostały przeprowadzone w tym samym roztworze. Charakterystyka mikrostruktury badanych stopów pokazuje matrycę Al; ciemnoszare, nieregularne wydzielenia fazy Mg 2 Si; oraz na granicach ziaren pręcikowe wydzielenia fazy Al 3 Ti, obecne w mikrostrukturze stopów AA 6063 z dodatkiem Ti. Ze wzrostem zawartości Ti, wydzielenia fazy Al 3 Ti stają się wydłużone i płytkowe. Wyniki testów korozyjnych wykazały, że szybkość korozji spadła w stopach zawierających mniej niż 1% Ti, a wzrosła w stopach zawierających więcej niż 1% Ti, niezależnie od tego, czy stopy były homogenizowane i starzone. Zaobserwowano, że obróbka cieplna podwyższa odporność stopów na korozję.

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à Ìåðñèíñêèé óíèâåðñèòåò, ôàêóëüòåò ìàøèíîñòðîåíèÿ, ×èôòëèê, Ìåðñèí, Òóðöèÿ á Êàôåäðà ìåòàëëóðãèè è ìàòåðèàëîâåäåíèÿ, ôàêóëüòåò ìàøèíîñòðîåíèÿ, Óíèâåðñèòåò Êûðûêêàëå, Êûðûêêàëå, Òóðöèÿ â Êàôåäðà ìåòàëëóðãèè è ìàòåðèàëîâåäåíèÿ, ôàêóëüòåò ìàøèíîñòðîåíèÿ, Óíèâåðñèòåò Êàðàáóêà, Êàðàáóê, Òóðöèÿ ã Ôàêóëüòåò ïðîôåññèîíàëüíî-òåõíè÷åñêîãî îáðàçîâàíèÿ, Óíèâåðñèòåò Êàðàáóêà, Êàðàáóê, Òóðöèÿ Èññëåäîâàíî âëèÿíèå ïðîöåññà ñòàðåíèÿ íà øåðîõîâàòîñòü ïîâåðõíîñòè è ìåõàíè÷åñêèå ñâîéñòâà àëþìèíèåâûõ ñïëàâîâ AA6061 è AA7075. Ìåõàíè÷åñêèå ñâîéñòâà èññëåäîâàëè ïðè èñïûòàíèÿõ íà ìèêðîòâåðäîñòü è ðàñòÿaeåíèå. Ïîâåðõíîñòü îáðàçöîâ èññëåäîâàëè ñ ïîìîùüþ ðåíòãåíîñòðóêòóðíîãî àíàëèçà. Ïîñëå èñïûòàíèÿ íà ðàñòÿaeåíèå ïîâåðõíîñòü ðàçðóøåíèÿ èññëåäîâàëè ìåòîäîì ðàñòðîâîé ýëåêòðîííîé ìèêðîñêîïèè. Âëèÿíèå ïðîöåññà ñòàðåíèÿ íà øåðîõîâàòîñòü ïîâåðõíîñòè èçó÷àëè ñ ïîìîùüþ àòîìíî-ñèëîâîãî ìèêðîñêîïà. Ïîêàçàíî, ÷òî ñ ðîñòîì øåðîõîâàòîñòè ïîâåðõíîñòè óâåëè÷èâàåòñÿ êîëè÷åñòâî âûäåëèâøèõñÿ ôàç.Êëþ÷åâûå ñëîâà: àëþìèíèåâûå ñïëàâû, àòîìíî-ñèëîâîé ìèêðîñêîï, ìåõàíè÷åñêèå ñâîéñòâà, ðàñòðîâàÿ ýëåêòðîííàÿ ìèêðîñêîïèÿ. Introduction.Aluminum alloys offering high strength-to-weight ratio, good formidability and high corrosion resistance are extensively used in various fields such as the aerospace and automobile industries [1][2][3][4][5][6][7][8]. Magnesium alloys, the lightest of the structural metals with a two-thirds density of aluminum alloys, have been extensively explored for practical industrial applications during the past decade [9][10][11]. The high strength-to-weight ratio makes utilization of 6xxx series Al alloys favorable for a wide variety of applications [10][11][12][13][14]. Various structural applications in automobile and aerospace

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