Tomasz Mikuszewski

Plasticity and Microstructure of Magnesium - Lithium Alloys

The article presents the results of tests connected with influence of strain parameters on the susceptibility to hot working of magnesium lithium alloys with lithium content of 7.5% mass. Plasticity tests were conducted in compression test from room temperature up to 400°C with strain rate of 0.1s-1. Conducted tests allowed for determination of susceptibility of magnesium alloys with different lithium content to hot working. The results were compared with typical alloy AZ31. The results of influence of deformation temperature on the microstructure of tested alloys are also presented in this paper.

Oxidation performance of Co–Al–W and Co–Ni–Al–W new type of γ-γʹ cobalt-based superalloys

Cobalt-based superalloys are class of new heat-resistant materials for components of turbine engines. The γ-γʹ phase microstructure similar to nickel-based analogue, provide excellent creep resistance as well as resistance to corrosion and oxidation. Superior high temperature resistance drives intensive development of Co-based superalloys. The aim of paper is assessment of high temperature oxidation behaviour of Co–9Al–9W and Co–20Ni–7Al–7W alloys in as-cast state. The non-isothermal oxidation performance of Co–9Al–9W and Co–20Ni–7Al–7W alloys was studied using thermogravimetric method up to 1200°C. The thermogravimetric analysis was carried out under argon atmosphere with heating rate 5°C/min. The scale morphology after high temperature oxidation test was investigated. The evaluation of scale concerned macrostructure, microstructure, chemical and phase composition of surface after high temperature oxidation tests. Surface of tested alloys after oxidation was characterized using X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and light microscopy (LM). Co–20Ni–7Al–7W was characterized by slightly better high temperature oxidation resistance than basic Co–9Al–9W alloy. The surface stability in elevated temperature is important factor in case of components undergoing elevated temperature. This paper shows possibilities of these alloys for high temperature service.

Structure and Hardness of the ZnAl40Cu(1-2)Ti(1-2) Alloys

The purpose of the examination was to determination of influence of microstructure and hardness of Zn-Al-Cu alloys with titanium addition. The subject of examination was were ZnAl40Cu2Ti, ZnAl40Cu1.5Ti1.5 and ZnAl40Ti2Cu alloys. The scope of test included Brinell hardness tests, tests on optical microscope, tests on scanning microscope and X-ray microanalysis. It was found that tested ZnAl40Cu(1-2)Ti(1-2) alloys are characterized by homogeneous, fine- grained structure. Carried out tests pointed out, that addition of titanium to ZnAl40Cu(1-2)Ti(1-2) alloy influences on hardness increasing. It was also found, that the titanium forms Ti-Al precipitates in ZnAl40Cu(1-2)Ti(1-2) alloys and does not take part in solution strengthening process.

The Influence of Molding Parameters on the Structure of the ZnAl40Cu2Ti Alloy

The aim of this study was to determine the influence of casting technology on the structure of the ZnAl40Cu2Ti alloy. The scope of the examination included Brinell hardness tests and tests on optical microscopy, scanning electronic microscope test and X-ray microanalysis. The tests showed that, depending on the casting technology can be obtained different ZnAl40Cu2Ti alloy structure, characterized by different chemical composition in microareas. It has been pointed out that in order to get ZnAl40Cu2Ti alloy modification of Zn-Al-Cu alloy used technology casting is necessary.

The Influence of Addition of the Rare Earth Elements on the Structure and Hardness of AlZn12Mg3.5Cu2.5 Alloy

Aluminium alloys are characterized by a number of advantageous properties , which include: low density ,high relative strength , high electrical and thermal conductivity , ease of machining and good dumping features. Particular interesting are high-strength aluminum alloys of zinc, magnesium and copper. These alloys are used mainly in aircraft, building &structure, electrical, electrical power and automotive industry. A significant problem associated with the use of high-strength aluminium-zinc alloys is their insufficient resistance to corrosion. Improvement of corrosion resistance can be obtained by application of alloy micro-additives. The article shows results of examinations related to influence of rare earth additive on the structure and hardness of AlZn12Mg3.5Cu2.5 alloy. The scope of examination included: structure testing using scanning microscope, X – ray microanalysis, hardness test. Examinations have shown higher hardness of samples with rare earth additives. Was found , that rare earth addition influences on more fine –grained structure of the AlZn12Mg3.5Cu2.5 alloy.