The specific heat capacity was calculated by DSC and the kinetics of oxidation was determined for alloys from the NiAl, FeAl and TiAl phase equilibrium system. The Ti48Al alloy contained an addition of 2 at.% of chromium and niobium. The highest value of heat capacity had the Ti-Al and Fe-Al alloys. At temperatures above 673K, the Ti48Al alloy showed an anomaly, that is, a lower value of the heat capacity. The change in heat capacity was related with an exothermic reaction. The oxidation of alloys was running according to either parabolic or cubic law. Alloys characterised by high thermal capacity showed a higher gain in weight. The slowest to oxidise was the Ni3Al intermetallic phase.

Abstract. In recent years, a development of AHSS steels for manufacturing parts for the automotive industry is the observed trend. The high-manganese steels with aluminium and silicon addition, exhibiting twinning induced plasticity (TWIP) effect, are one of the most interesting modern materials, due to their unique combination of both very good strength and great ductility. However, the material behaviour during plastic deformation depends not only on the chemical composition but also on deformation conditions, inter alia, strain rate and temperature. TWIP steels can be used for production of energy-absorbing parts, therefore it is very important to analyse their deformation behaviour at high strain rates. The paper presents the effect of deformation in quasi-static and dynamic conditions on the microstructure of an experimental TWIP steel. The experiments were performed on tensile testing machine and on the flywheel machine. The microstructure was analyzed by optical and scanning transmission electron microscopy. Thanks to the measurements during the quasi-static test and numerical simulations of both tensile tests, the temperature increase was determined in the sample region from which the sections for microstructural studies were taken. It was found that the temperature increase in dynamic conditions can affect the microstructure evolution in the investigated TWIP steel.

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