The deformation mechanisms and mechanical properties of Fe-Mn-C-Al twinning-induced plasticity (TWIP) steels with a chemical composition range of 12–18 wt% Mn and 0–3 wt% Al, are reviewed. The in-depth microstructural analysis revealed that all the investigated TWIP steels exhibit deformation twinning as the main deformation mechanism in addition to dislocation glide. The Al-free TWIP steels have a much more complex deformation behavior than the Al-added TWIP steels. The deformation of Fe-15Mn-0.6C steel is accompanied by the formation of a very small amount of strain-induced e martensite, in addition to deformation twinning. Deformation of Fe-12Mn-0.6C steel is accompanied by several deformation mechanisms which are simultaneously activated: strain-induced e martensite, formation of shear bands and strain-induced α′ martensite, in addition to deformation twinning. The upper limit for the value of SFE for strain-induced martensitic transformation is determined to be approximately 13 mJ/m 2 . The results confirm that the SFE is the key parameters affecting the strength and the ductility of TWIP steel. A linear relation between the ultimate tensile strength (UTS) and the SFE is proposed, with the UTS increasing with decreasing SFE.

Stacking fault energy and deformation mechanisms in Fe-xMn-0.6C-yAl TWIP steel

Thermal sprayed Fe-based amorphous coatings exhibit excellent wear and corrosion resistance, and thus have been widely utilized for enhancing the performance of material surfaces. In this paper, important research progresses achieved in regards to deposition technologies and properties of thermal sprayed Fe-based amorphous coatings are reviewed. In particular, the dependence of wear and corrosion resistance of the coatings on processing parameters, e.g., kinetic energy, particle size, gas flow rate, and heat treatment temperature are summarized. Moreover, the utilization of reinforced phases and alloy elements for enhancing the wear and corrosion resistance of the coatings are presented. It is expected that future endeavors will be dedicated to the formation mechanism of amorphous phase and “processing parameter-microstructure-macroscopic property” relationship of Fe-based amorphous coatings.

Wear and corrosion resistant performance of thermal-sprayed Fe-based amorphous coatings: A review

Inconel 718 is widely used because of its ability to retain strength at up to 650 ∘C for long periods of time through coherent metastable 𝛾   Ni 3Nb precipitation associated with a smaller volume fraction of 𝛾  Ni 3Al precipitates. At very long ageing times at service temperature, 𝛾   decomposes to the stable Ni 3Nb 𝛿 phase. This latter phase is also present above the 𝛾   solvus and is used for grain control during forging of alloy 718. While most works available on 𝛿 precipitation have been performed at temperatures below the 𝛾   solvus, it appeared of interest to also investigate the case where 𝛿 phase precipitates directly from the fcc matrix free of 𝛾   precipitates. This was studied by X-ray diffraction and transmission electron microscopy (TEM). TEM observations confirmed the presence of rotation-ordered domains in 𝛿 plates, and some unexpected contrast could be explained by double diffraction due to overlapping phases.

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TEM Study of High-Temperature Precipitation of Delta Phase in Inconel 718 Alloy

Corrosion, wear and tribocorrosion performance of a thermally sprayed aluminum coating modified by plasma electrolytic oxidation technique for offshore submerged components protection

The purpose of this article is to investigate the relationship among the material design, in situ synthesis, microstructure and mechanical properties of arc-sprayed Al-Ni-Ti amorphous coatings. The precursor reactants were designed by aluminium strip and low-purity industrial alloy powders. The results show that the Al-Ni-Ti coating displays a lamellar structure with porosity up to 1%. The volume fraction of the amorphous, crystallization temperature and hardness of the coatings are 85.9%, 365°C and 4.87 GPa, respectively. The microstructure analysis reveals that the grey region in the coating has a glassy structure and the white region has a crystalline structure of α-Al phase. In 0.6 M NaCl solution, compared with the crystalline structure of the arc-sprayed Al coating and 6061-Al alloy, the Al-Ni-Ti amorphous coating demonstrates an extraordinarily higher pitting potential (− 0.12 V) and lower corrosion current density (4.54 × 10−8 A/cm2). These investigations show that the present Al-Ni-Ti amorphous coating furnishes valuable guidance for expanding engineering applications with an inexpensive, high glass formation ability and prominent performance.

Development and Characterization of Al-Based Amorphous Coating

High corrosion and wear resistance of Al-based amorphous metallic coating synthesized by HVAF spraying

Impact of gas pressure on particle feature in Fe-based amorphous alloy powders via gas atomization: Simulation and experiment

High-resolution image simulation of overlap structures in TiAl alloy

The effects of solution concentration and temperature on the electrochemical behavior of the Fe-based amorphous (AMCs) coatings in NaCl solution were studied by using conventional electrochemical measurement and XPS analysis. Results indicated that as solution concentration and temperature increased, the current density for the Fe-based AMCs increased and the pitting potential decreased. This reduced corrosion resistance was derived from the decreased passivation index and polarization resistance, which contributed to the decrease of the induction time (tm) for the initiation of corrosion pit. The passive films formed on Fe-based AMCs exhibit two types’ semiconductors higher and lower the flat band potential. The decrease of protectiveness of the passive film was mainly correlated with the reduction of Cr2O3 content, the increase of carrier density and the decrease of the work function (WF).

Weiyan Lu

Papers

High corrosion and wear resistance of Al-based amorphous metallic coating synthesized by HVAF spraying

Impact of gas pressure on particle feature in Fe-based amorphous alloy powders via gas atomization: Simulation and experiment

High-resolution image simulation of overlap structures in TiAl alloy

Sensitivity of Corrosion Behavior for Fe-Based Amorphous Coating to Temperature and Chloride Concentration

TEM observations of twin intersections in a Ti-47Al-2Cr-2Nb-0.1Y alloy compressed at room temperature