The Composition Control And Properties Of High Entropy Alloys Containing FeSiB

The high entropy alloys (HEAs) with unique structures have excellent propertiesincluding high hardness, work hardening capacity, thermostability, good corrosion resistance,wear resistance and other characteristics. All of the characteristics make HEAs can be used inspecific situations instead of existing alloys. Therefore, the research about HEAs as a newfield of the alloy has profound academic and application values. In this paper, we reportFeSiBAlNi HEAs determined from the prototype of Fe-Si-B metallic glasses with good softmagnetic properties. The connections had been studied between the intrinsic properties aswell as the size effect and the microstructures of FeSiBAlNi HEAs when Nb, Cu, Co and Agwere added in order to optimize the composition design and obtain amorphous HEAs.In this paper, the effect of milling duration and composition on the microstructure,thermostability as well as magnetic properties of HEAs during mechanical alloying had beeninvestigated using X-ray diffraction, differential scanning calorimetry, scanning electronmicroscopy, transmission electron microscopy, alternating gradient magnetometry andelectrochemical workstation. At the same time, the mechanism has been discussed about theelements with similar atomic size but different structures and the formation of amorphousHEAs. The effect of aging treatment on the microstructures and properties of HEAs isinvestigated also. In addition, a rimary study of the FeSiBAlNi HEAs have been sinteredusing spark plasma sintering (SPS) at different temperatures．Then, the microstructure,thermodynamic properties as well as ocean corrosion resistance were invested. The specificresults are as follows:The results show that, the amorphous HEAs FeSiBAlNi, FeSiBAlNiNb, FeSiBAlNiCuand FeSiBAlNiCo had been successfully prepared by MA method, but the FeSiBAlNiAgHEAs was composed of a part of the amorphous as well as solid solutions phases. Theaddition of the sixth principal components shortened the amorphous formation timeobviously.For the HEAs systems, the thermal stability falling is as follows: FeSiBAlNiNb>FeSiBAlNiCo> FeSiBAlNi> FeSiBAlNiCu≈FeSiBAlNiAg by the Txfrom DSC curves.The results show that the addition of Nb and Co with high melting point not only raises the melting point but also improves the thermal stability of HEAs. However, the addition of Cuand Ag with low melting point reduces the thermal stability of HEAs.Moreover, the as-milled HEAs powders are semihard magnetic materials indicated bytheir coercivities which are higher than10Oe. It should be noticed that the as-milled productswith solid solutions phases show the better semihard magnetic properties than those with fullyamorphous phases. In the initial milling time, the saturation magnetization (Ms) values are asfollows: FeSiBAlNi> FeSiBAlNiCo> FeSiBAlNiCu> FeSiBAlNiANb> FeSiBAlNiAg，implying that the addition of the sixth components did not improve the magnetic property ofHEAs.The effect of aging treatment on the microstructures and properties of HEAs isinvestigated. It shows that the FeSiBAlNi(Nb/Cu/Co/Ag)HEAs exhibit different productions.But the major products are still solid solutions phases, at the same time, there are some metalcompounds existing. The results are as follows: The aging treatment simplifies the meltingbehavior of the FeSiBAlNi HEAs and the semihard magnetic property declines at first andrises after then. It makes the phase structures complexed with no obvious change of themelting model for the FeSiBAlNiNb HEAs at high aging treatment. FeSiBAlNiCu HEAs,generating some compounds as well as solid solutions phases making a rising for the meltingpoint, and the semihard magnetic properties increased before a decrease.FeSiBAlNiCo HEAs, there were solid solutions phases appeared and the magneticproperty increased after aging. The crystallization products of FeSiBAlNiAg HEAs shownexcellent heat resisting properties. The FeSiBAlNi HEAs after SPS have been investigatedand the results of microstructure and properties show that there were no complex phases andcompounds appeared. Instead, simple FCC/BCC generated. It also can be seen that the samplehad better ocean corrosion resistance sintered at high temperature than that at lowertemperature.