Production of nanosized composite Al-Fe-Cr-Ti alloys and study of their plasticity in the temperature range

DOI: 10.62564/M4-MI1128

Mykola Iefimov, Nataliia Zakharova, Svitlana Chugunova, Alex Golubenko, Victor Goncharuk

Frantsevich Institute for Problems of Materials Science National Academy of Science of Ukraine


The technological and physical principles for production of nanoquasicrystalline (QC) Al-Fe-Cr-Ti alloys with an increased level of mechanical properties have been developed. The strength of such alloys is provided by high hardness and elastic modulus of QC well as their stability up to relatively high temperatures, plasticity ensured by a special deformation mechanism of QC nanoparticles. The Al₉₄Fe₂.₅Cr₂.₅Ti₁ rods are produced using powder extrusion technology without sintering of high-pressure water atomization powders. The TEM and X-ray methods were used to characterize the structure; the mechanical properties were studied by indentation and mechanical tensile tests. To characterize the behavior of the Al-Fe-Cr-Ti alloys the physical plasticity characteristic δ* was first used. δ* is the ratio of plastic strain to total strain was determined both during indentation and tensile tests. It is shown that Al-Fe-Cr-Ti alloys have record heat resistance characteristics at 300°C: UTS 345MPa, YS 330MPa and elongation 4%, with elongation at room temperature up to 8%. The Al-Fe-Cr-Ti alloys show an abnormal behavior of plasticity change: with increasing temperature, the value of elongation δ gradually decreases in the temperature range of 20-300°C and with further temperature increase its value increases again. This effect is explained by the processes of dynamic strain aging (DSA) which is the instability of the plastic flow of materials associated with the interaction of moving dislocations and diffusing dissolved substances [1]. The δ*(δн) determined both tensile and hardness tests behave without taking into account the DSA effect: δ* and δн increase monotonically with increasing temperature. Thus, the use of δ* to characterize the change in plasticity in the temperature range allows us to characterize the plasticity of the material without considering the processes accompanying its fracture.

Keywords
nanoquasicrystals, structure, mechanical properties, plasticity

Acknowledgments
Not provided

References
[1] S. Pedrazzini, M. Galano, F. Audebert, G.D.W. Smith, Elevated Temperature Mechanical Behaviour of Nanoquasicrystalline Al93Fe3Cr2Ti2 Alloy and Composites, Materials Science and Engineering A, 2017. V.705. P.352-359.