Fe-based bulk metallic glasses (BMGs) have attracted much attention due to their combinations of properties, such as high strength and hardness, superior corrosion resistance, good magnetic properties, and relatively low material cost. Nowadays, numerous research works have been devoted to the glass forming ability (GFA) of Fe-based BMGs, and some new Fe-based alloys with high GFA has been developed. Searching for alloys with new composition has been a tedious and costly process since too much experimental works are needed. Therefore, it is of importance to put forward a new rule or a method for guiding the development of new Fe-based glassy alloys on the basis of the structure of metallic glasses. On the other hand, the brittle feature of BMGs at room temperature greatly restricts their application as prospective structural materials. In this paper, a new method that can be used to predict the Fe-based glassy alloy compositions is proposed. Moreover, Fe-based amorphous metallic coatings have been explored in order to promote their practical application in surface engineering area.
The main results are as follows:
(1) High performance Fe based amorphous metallic coatings were produced by by High Velocity Oxygen Fuel (HVOF) thermal spraying. The coatings had high hardness and high wear resistance compared to Ni-based amorphous metallic coatings and electroplated Cr. In 1 mol/L HCl aqueous solution, the coating demonstrated a wide passive region and a low passive current density. The corrosion resistance is enhanced with the increase of coating thickness. The volume fraction of amorphous phase in the coatings affects their spontaneous passivation behaviors. The anti-corrosion property is increase with the amorphous contents. In addition, the coatings exhibit paramagnetic behavior at room temperature.
(2) Based on electronegativity differentia and MECP model, a simple method for searching Fe-based glassy alloy composition was developed. A new composition Fe70.4Nb4.8Y2.8B22 was predicted in terms of Δx - ΔTx relationship. The maximum diameter for Fe-based glassy sample is up to 3 mm with a large supercooling of 65 K.
(3) A protocol λ rule for evaluating the GFA of Fe-based BMGs was formulated. It shares that compositions have higher GFA when λ is closer to λbest. This rule is consistent with the ΔTx rule.
修改评论