The effect of anisotropic as-cast microstructure on high-temperature compression deformation of multiphase Co24Cr19Fe24Ni19Al8(Ti,Si,C)6 (at.%) complex concentrated alloy (CCA) derived from a single phase CoCrFeNi based high entropy alloy (HEA) was studied at temperatures ranging from 750 to 900 • C. The highly anisotropic microstructure composed of several columnar grains with [100] crystallographic direction parallel or nearly parallel to the load axis leads to asymmetric barrelled shapes of the compression specimens with multiple protuberances on the barrelled surfaces. The experimental barrelled shapes differ from the numerically calculated ones. The deformation curves exhibit strain hardening stage which is followed by a deformation at a constant flow stress at all studied temperatures. The work hardening rate (WHR) first increases with increasing strain. After achieving a peak value, the WHR decreases and achieves values around zero corresponding to the steady-state deformation. The finite element analysis (FEA) of 3D distribution of local equivalent strains and stresses corresponds qualitatively quite well to the observed structural changes within the barrelled specimens. K e y w o r d s : complex concentrated alloys, high-entropy alloys, anisotropy, plastic deformation, mechanical properties, finite element modelling

The effect of hydrogenation on room temperature tensile deformation behaviour of ferritic-pearlitic steel was studied. The process of hydrogenation was realised by annealing in flowing hydrogen followed by a fast cooling to room temperature. The room temperature tensile deformation behaviour of hydrogenated and annealed specimens was studied by the digital image correlation (DIC) method. Tensile elongation and reduction of the area were measured on the surface of cylindrical specimens coated with random speckle patterns using stereo CCD camera system. DIC elongation data were related to the data measured by an extensometer touching the specimen gauge section. The data from the DIC method were used for calculations of true stress-true strain tensile curves. Numerical simulations of strain fields within the gauge region of the specimens using finite element method were validated by the experimental data from the DIC method.

The effect of carbon content x ranging from 1.4 to 3.6 at.% on the room temperature compressive behaviour of Ti-44.5Al-8Nb-0.8Mo-xC (at.%) alloys prepared by vacuum induction melting has been studied. The microstructural analysis by SEM shows that the increase of the carbon content increases the volume fraction of the reinforcing carbide particles and leads to a change of the matrix microstructure from α2(Ti3Al) + γ(TiAl) + β/B2 to γ type. The carbon content affects the morphology and size of the primary plate-like, regular and irregular shaped Ti2AlC particles. The finite element analysis (FEA) of local equivalent strains and quantitative metallography analysis indicate that the mean size of fragmented carbide particles decreases with increasing local equivalent strain in the compression specimens. The differences in work hardening behaviour of the compression specimens with various content of carbon are related to the initial non-uniform deformation, cracking of primary carbide particles, crack propagation and release of some grains from the free surface during compression testing.