Erratum to: Effects of Nickel on the Oxide/Metal Interface Morphology and Oxidation Rate During High-Temperature Oxidation of Fe–Cu–Ni Alloys

Steel produced in an electric arc furnace (EAF) contains a high amount of Cu that causes a surface-cracking phenomenon called surface hot shortness. Ni reduces the risk for surface hot shortness, and this work focuses on investigating the following two phenomena caused by Ni during oxidation at 1150 °C for Fe–Cu–Ni alloys: (1) the decrease in oxidation rate and (2) the formation of a wavy liquid-Cu/oxide and of liquid-Cu/γ-iron (γFe) interfaces, which promote Cu occlusion into the scale. Thermogravimetry, scanning electron microscopy, and transmission electron microscopy-energy dispersive spectroscopy techniques were applied. A numerical model also was developed to explain the experimental results. High Ni contents cause higher liquid-Cu/γFe interface nickel concentrations and more potential for an interface breakdown. The decrease in oxidation rate by adding nickel can be explained qualitatively by the decrease in Fe cation transport through the wüstite layer.     

Structural State of High-Entropy Fe40–xNiCoCrAlx Alloys in High-Temperature Oxidation

Powder Metallurgy and Metal Ceramics - The evolution of phase composition and mechanical properties and the formation of oxide layers on Fe40–xNiCoCrAlx (x = 5 and 10 at.%) alloys in...     

Effect of Cr and Ni/Fe Ratio on the Microstructure and Mechanical Properties of γ′-Strengthened Ni–Fe-Based Alloys

Metallurgical and Materials Transactions A - To continue to meet the future materials’ requirements for advanced power generation systems, enhancing the mechanical properties and long-term...     

Sintering of Tungsten and Tungsten Heavy Alloys of W–Ni–Fe and W–Ni–Cu: A Review

Tungsten is a refractory metal possessing good mechanical properties of high strength, high yield point, and high resistance to creep. Therefore, tungsten and its alloys are used in many high temperature applications. Due to the high melting point, they are generally processed through powder metallurgy method. The powders are compacted using die pressing or isostatic pressing. The compacts are sintered in a sintering furnace to achieve high density, thereby, making the metal suitable for further processing. This article reviews the recent research findings of consolidating tungsten and its alloys (W–Ni–Fe and W–Ni–Cu), from preparation of powder alloys to sintering of the compact. The advances in sintering are based on the objective of achieving good densification of the metal at lower temperature and at faster rate. The use of microwave sintering and spark plasma sintering techniques resulted in significant reduction in sintering time and producing products of good mechanical properties.     

Solidification Behaviour of Ti–Cu–Fe–Co–Ni High Entropy Alloys

For the first time, we report here that the development of the novel Ti?CCu?CFe?CCo?CNi high entropy alloys (HEAs) via vacuum arc melting technique using non consumable tungsten electrode under high purity Ar atmosphere on a water-cooled copper hearth. Ti?CCu?CFe?CCo?CNi multicomponent alloys with varying Ti/Cu (x) molar ratio (x?=?1/3, 3/7, 3/5, 9/11, 1, 11/9 and 3/2) have been prepared through the tailoring of microstructure to get understanding of the phase formation and the microstructural evolution of these multicomponent HEAs. X-ray diffraction and scanning electron microscopy coupled with energy dispersive spectroscopic results confirm the presence of (Cu)_ss, (Co)_ss and (??-Ti)_ss dendrites with ultrafine eutectic between cubic (Cu)_ss and Laves phase (Ti₂Co type). The solidification pathways of novel alloys are critically discussed as follows. For x?=?9/11, 1, 11/9 and 3/2; firstly, (??-Ti)_ss dendrite is formed from the liquid, followed by the liquid phase separation between the cobalt-rich solid solution (Co)_ss and copper-rich solid solution (Cu)_ss and finally, the remaining liquid undergoes eutectic reaction between copper solid solution (Cu)_ss and the Laves phase (Ti₂Co Type), whereas for x?=?1/3, 3/7 and 3/5; (??-Ti)_ss dendrite is formed first from the liquid and then remaining liquid undergoes the liquid phase separation resulting two different dendrites of (Cu)_ss and (Co)_ss phases. Detailed thermodynamic calculations have been carried to rationalize the formation of stable solid solution phases of these newly developed multicomponent Ti?CCu?CFe?CCo?CNi HEAs.     

Amorphous Intergranular Film Effect on the Texture and Structural Evolution During Cold-Rolling of Nanocrystalline Ni–Zr Alloys

Metallurgical and Materials Transactions A - The presence of amorphous intergranular films (AIFs) in nanocrystalline (NC) metals improves the mechanical properties and thermal stability. However,...     

Features of the Sintering of Fe–Cu–Sn–Ni and Cu–Ti–Sn–Ni Powders during Hot Pressing

Powder Metallurgy and Metal Ceramics - The efficiency and durability of a diamond tool fabricated using powder metallurgy methods depend on several factors. These are the quality of diamond...     

Mechanisms of the Origin of Fine and Non-Dendritic Grains at the Sonotrode–Liquid Metal Interface During Ultrasonic Solidification of Metals

Proposed grain refinement mechanisms during ultrasonic solidification have been explained in terms of refinement between cavitation enhanced nucleation and fragmentation of dendrites according to the casting conditions. Solidification studies also describe the activation of nucleation under pressure pulses after bubble implosion as an additional supporting mechanism for grain refinement. This study clarifies some overlooked concepts and proposes a plausible grain refinement mechanism explaining the role of cavitation in pure Zn and a Mg–6 wt pct Zn alloy. Equivalent grain size and grain density have been obtained in pure Zn and the Mg–6 wt pct Zn alloy (grain size distribution ranging from 40 to 200 µm) when UST was applied after the onset of solidification. These fine, non-dendritic grains originate from the cavitation zone beneath the sonotrode. Significant thermal undercooling surrounding the low superheat sonotrode in contact with the melt is responsible for the formation of a solidified layer (typically the thickness is equivalent to the average grain diameter) at the sonotrode–melt interface. High-frequency vibrations with or without cavitation at this interface assist the separation of these fine grains, which are then carried into the melt by acoustic streaming. A possible mechanism for the separation of fine grains produced from the cavitation zone is explained with the help of established concepts reported for the ultrasonic atomization process.

     

Developing Dislocation Subgrain Structures and Cyclic Softening During High-Temperature Creep–Fatigue of a Nickel Alloy

The complex cyclic deformation response of Alloy 617 under creep–fatigue conditions is of practical interest both in terms of the observed detriment in failure life and the considerable cyclic softening that occurs. At the low strain ranges investigated, the inelastic strain is the sole predictor of the failure life without taking into consideration a potentially significant environmental influence. The tensile-hold creep–fatigue peak stress response can be directly correlated to the evolving dislocation substructure, which consists of a relatively homogenous distribution of subgrains. Progressive high-temperature cycling with a static hold allows for the rearrangement of loose tangles of dislocations into well-ordered hexagonal dislocation networks. The cyclic softening during tensile-hold creep–fatigue deformation is attributable to two factors: the rearrangement of dislocation substructures into lower-energy configurations, which includes a decreasing dislocation density in subgrain interiors through integration into the subgrain boundaries, and the formation of surface grain boundary cracks and cavity formation or separation at interior grain boundaries, which occurs perpendicular to the stress axis. Effects attributable to the tensile character of the hold cycle are further analyzed through variations in the creep–fatigue waveform and illuminate the effects of the hold-time character on the overall creep–fatigue behavior and evolution of the dislocation substructure.     

Effect of Cooling Rate on the Microstructure of Semi-Solid Al–25Si–2Fe Alloy During Electromagnetic Stirring

The effect of cooling rate on the microstructure of semi-solid Al–25Si–2Fe alloy was investigated during electromagnetic stirring. It was found that as the cooling rate was increased from 7 to 21 °C/min, the equivalent diameter of the primary Si particles decreased from 70 ± 5 to 25 ± 2 μm. The primary Si particles form a fine blocky structure when the cooling rate is 21 °C/min. When the cooling rate is increased to 30 and 33 °C/min, the primary Si particles coarsen and adopt plate or other irregular shapes. As the melt cools to 690 °C, Fe inter-metallic phases present different morphologies at different cooling rates during EMS. These phases in the Al–25Si–2Fe alloy are mainly in the form of δ-Al₄FeSi₂ at higher cooling rates.     

Effect of Vacuum Hot Pressing Temperature on the Mechanical and Tribological Properties of the Fe–Cu–Ni–Sn–VN Composites

Powder Metallurgy and Metal Ceramics - The mechanical (hardness and elastic modulus) and tribological (friction force and wear rate) properties of the Fe–Cu–Ni–Sn–VN...     

Influence of the Oxygen Induced Surface Segregation Process of Solutes on the Anti-corrosion Properties of the Fe–Cr and Fe–Cr–Si Alloys

Metallurgical and Materials Transactions A - The influence of the oxygen-induced surface segregation process of Cr and Si solutes on the anti-corrosion properties of Fe–Cr and...     

The Effect of Cooling Rate on the Strength of Sintered Fe—Cu Compacts

Abstract

The effect of cooling rate from the sintering temperature upon the tensile strength of compacts from a mixture of iron and copper powder was investigated. The compacts were pressed at 450 and 390 MPa and sintered in hydrogen at 1120°C for 40 min. The copper content of the compacts varied from 0 to 12%. For alloys with Cu content >4% the tensile strength was found to be strongly dependent upon the cooling rate in the temperature range between 850 and 600°C, with rapidly cooled specimens being considerably stronger. In specimens with 8%Cu the tensile strength increased from 206 to 343 MPa when the cooling rate was increased from 10 to 200 degC min^?1. In specimens with 2%Cu cooling rates above and below 600 degC min^?1 appear to influence the tensile strength. Possible explanations for the observed effects of cooling rate upon tensile strength in sintered Fe–Cu alloys are discussed.     

Effect of Microstructure,Strain Rate,and Elevated Temperature on the Compression Property of Fe–Co–Ni–Cr–Zr Alloy

Metallurgical and Materials Transactions A - Eutectic high-entropy alloys with FCC solid solution phase and hard Laves phase can be used as potential structural materials to meet the service...