https://dc.engconfintl.org/cgi/viewcontent.cgi?article=1032&context=superalloys_ii

A critical review of high entropy alloys and related concepts

High-entropy alloys (HEAs) are alloys with five or more principal elements. Due to the distinct design concept, these alloys often exhibit unusual properties. Thus, there has been significant interest in these materials, leading to an emerging yet exciting new field. This paper briefly reviews some critical aspects of HEAs, including core effects, phases and crystal structures, mechanical properties, high-temperature properties, structural stabilities, and corrosion behaviors. Current challenges and important future directions are also pointed out.

https://www.tandfonline.com/doi/pdf/10.1080/21663831.2014.912690

High-Entropy Alloys: A Critical Review

Prediction of high-entropy stabilized solid-solution in multi-component alloys

Microstructure and Room Temperature Properties of a High-Entropy TaNbHfZrTi Alloy (Postprint)

Microstructure and wear behavior of AlxCo1.5CrFeNi1.5Tiy high-entropy alloys

An AlCrFeCoNi high entropy alloy was prepared by vacuum arc melting. Only diffraction peak corresponding to a BCC crystal structure is observed for this AlCrFeCoNi high entropy alloy. The microstructure of this AlCrFeCoNi alloy is polygonal grains with intragranular dendritic segregation. Dendritic segregation area is found to be Al, Ni rich and Cr, Fe deplete, while interdendritic segregation area is Cr, Fe rich and Al, Ni deplete. The distribution of Co is essentially identical. The fine microstructure of dendritic segregation area and of interdendritic segregation area is found to be nanoscale spherical precipitates morphology and basket-weave morphology, respectively. Results of EDS attached on high resolution scanning electron microscope (SEM) revealed that these morphological characteristics are also resulted from elements segregation. This AlCrFeCoNi high entropy alloy exhibits excellent compressive properties. The yield stress, compressive strength and plastic strain of the alloy reaches 1250.96, 2004.23 MPa, and 32.7%, respectively. The fracture mechanism of this AlCrFeCoNi high entropy alloy is observed as cleavage fracture and slip separation.

Microstructure and compressive properties of AlCrFeCoNi high entropy alloy

Mn, Ti and V were added in an equal-molar ratio to the AlCrFeCoNiCu alloy and the effects of these added elements on microstructure and properties of AlCrFeCoNiCu high entropy alloy were studied. The results indicate that the AlCrFeCoNiCuMn alloy shows almost the same microstructure as in AlCrFeCoNiCu alloy except for a long-strip Cr-enriched phase. The additions of Ti change the AlCrFeCoNiCu alloy from a dendrite structure to eutectic-cell one. Hence two phases in the eutectic cells are detected as one Al, Ti, Co, Ni enriched phase and another Cr, Fe enriched phase. V added alloy is also a dendrite structure, but V additions change the morphology of dendritic area from modulated plates to ellipsoidal particles. The addition of V into the AlCrFeCoNiCu alloy shows the best strengthening effect and the lowest decrease in the ultimate strain in our experiments.

Effects of Mn, Ti and V on the microstructure and properties of AlCrFeCoNiCu high entropy alloy

The invention provides a high-entropy alloy based composite material and a method for preparation, which relates to an alloy composite material and a method for preparation. The invention provides the high-entropy alloy based composite material and a method for preparation, and a composite material whose comprehensive performance is better than high-entropy alloy. The high-entropy alloy based composite material is made from 1-45 percent of reinforced phase and 55-99 percent of high-entropy alloy base according to the volume percentage. The high-entropy alloy based composite material is prepared by an in-situ spontaneity method or a non- in-situ spontaneity method, and the reinforced phase is prepared in an original position in the high-entropy alloy base or is added from the outer portion. The invention further improves the mechanical properties of materials basing on original high-entropy alloy, and is capable of playing the potentiality of the high-entropy alloy base in maximum limit. The high-entropy alloy based composite material of the invention is capable of being used by various preparation processes, the operation is easy and is easy to operate.

High-entropy alloy-base composite material and preparation method thereof

To consider a sessile drop on an ideal solid surface in equilibrium with a vapor phase, the classic Young equation was given. The derivation of the Young equation was based on both the mechanics and the energy knowledge. According to the constant volume of the liquid in the wetting process of the liquid on a smooth and homogeneous solid surface and the low energy law, Young equation was obtained through the mathematic method in this paper. The previous work indicated that the contact angle θ was a function of time, but the coefficient can be obtained only through experiments. It was assumed that the liquid was steady Newtonian flow. Then the relationships between the dynamic contact angles and the wetting time were found in terms of the equilibrium of the spreading force and the restoring force. An immediate theoretical justification for the dependence of contact angles and the time was given. It was assumed that the effect of the gravity on wetting was negligible in the investigation. Under what conditions was the gravity negligible? The criterion of the gravity on the wetting process of the liquid was proposed when contact angles were greater than 90°. If the criterion, I, was much smaller than 1, the effect of the gravity on the wetting process could be ignored. If the criterion, I, was equal to or larger than 1, the effect of the gravity on the wetting process could not be ignored. On mercury-mica systems, the gravity may be considered only when the equilibrium contact radius reached 1.5 mm.

Kinetics of wetting of liquid on a solid surface

The invention relates to a preparation method of a gypsum mould for the precision casting of a micro-melting mold, pertaining to a gypsum mould preparation method. The invention solves the problem that: the gypsum mould produced by the current preparation method can not meet the requirements for the precision casting of micro-melting and be used for casting once-forming micro elements which have finish surface and high size accuracy. The preparation method is that: 1. Alpha or Beta semi-hydraulic gypsum and deionized water are mixed and stirred; 2. the gypsum slurry mixed and stirred in step one is poured into a water-proofing model and applied by ultrasonic field; 3. micro-melting investment casting gypsum mould is obtained after the ultrasonic field is stopped and the gypsum slurry is placed in the air and at room temperature. The method of the precision casting of the micro-melting gypsum mould adopted by the invention changes crystal microstructure of the solidified gypsum slurry by means of adding physical field and reduces the crystal size so as to produce the gypsum mould which meets the requirement of micro-melting investment casting, and cast once-forming micro elements with bright surface and high size accuracy.

Mingxing Ren

Papers

Microstructure and compressive properties of AlCrFeCoNi high entropy alloy

Effects of Mn, Ti and V on the microstructure and properties of AlCrFeCoNiCu high entropy alloy

High-entropy alloy-base composite material and preparation method thereof

Kinetics of wetting of liquid on a solid surface

Preparation method of micro-welding mould quick used plaster casting mold