Jiangbo Cheng

Bio: Jiangbo Cheng is an academic researcher from Hohai University. The author has contributed to research in topics: Coating & Microstructure. The author has an hindex of 20, co-authored 55 publications receiving 975 citations. Previous affiliations of Jiangbo Cheng include Shanghai Jiao Tong University.

Effect of Nb addition on the structure and mechanical behaviors of CoCrCuFeNi high-entropy alloy coatings

Abstract: The microstructure and mechanical properties of the CoCrCuFeNiNb high-entropy alloy coating prepared by plasma transferred arc cladding process were investigated. Two phases are found in the prepared coating with Nb: one is face-centered-cubic solid solution phase; the other is the Laves phase of (CoCr) Nb type. The nano-indentation testing indicates that the microhardness (H), elastic modulus (E), the hardness/modulus of elasticity ratio (H/E ratio) and high resistance to plastic deformation (H3/E2) of the coating with Nb are 6.13 GPa, 221 GPa, 0.028 and 4.7 × 10− 3 respectively. The CoCrCuFeNiNb coating displays excellent wear and corrosion resistance. The wear resistance of the coating with Nb is about 1.5 times higher than that of the coating without Nb under the same wet sand rubber wheel abrasion testing conditions. Compared with the coating without Nb and as-cast 304 stainless steel, the coating with Nb shows the lowest icorr values in polarization curves and the highest fitted Rf values in EIS plots in 6N hydrochloric acid solution.

Evolution of microstructure and mechanical properties of in situ synthesized TiC–TiB2/CoCrCuFeNi high entropy alloy coatings

Abstract: The aim of this paper was to explore a one-step in situ method to synthesize the TiC–TiB 2 reinforced CoCrCuFeNi high entropy alloy composite coatings. In this method, the composite coatings were prepared by plasma transferred arc cladding process using Ti, B 4 C, Co, Cr, Cu, Fe, and Ni powder mixture as precursors. The effects of CoCrCuFeNi(Ti, B 4 C) x (x in molar ratio, 0.1 ≤ x ≤ 0.5) additions on the structure and mechanical properties of the coatings were investigated. For 0.1 ≤ x ≤ 0.2, the coatings induce the formation of face-centered cubic (FCC) and body-centered cubic (BCC) plus TiC structures. Further addition of x content (0.3 ≤ x ≤ 0.5), promotes high volume fraction of dual-phase TiC–TiB 2 embedded in FCC and BCC matrix. There are also corresponding variations in mechanical properties with structural evolutions. For CoCrCuFeNi(Ti, B 4 C) 0.1 coating, the nanohardness ( H ) and Young's modulus ( E ) are 4.19 and 234 GPa, respectively. These properties are further improved as function of x content ( H = 9.14 GPa and E = 261 GPa are achieved in CoCrCuFeNi(Ti, B 4 C) 0.5 coating). The mechanical hardening is accompanied with an increase of the ratio of hardness to elastic modulus ( H / E ), the yield pressure ( H 3 / E 2 ) and the elastic recovery ( η value). An attempt has been made to co-relate the wear resistance of the coatings with H / E ratio and η value.

Formation and Mechanical Properties of CoNiCuFeCr High-Entropy Alloys Coatings Prepared by Plasma Transferred Arc Cladding Process

Abstract: Plasma transferred arc cladding process was used to fabricate CoNiCuFeCr multi-element alloys coatings. The experimental results show that the coating forms a face-centered-cubic solid solution phase. The microstructure of the coating is mainly composed of dendrite and discontinuous interdendritic segregation. The average hardness of the coating reaches 194.8 HV100. The nano-indentation testing indicates that the micro-hardness and elastic modulus of the coating are 3.64 GPa and 211 GPa, respectively. The CoNiCuFeCr high-entropy alloy coating has excellent wear and corrosion resistance. The wear resistance of the coating is about 1.7 times higher than that of Q235 steel substrate under the same wet sand rubber wheel abrasion testing conditions. In 1N hydrochloric acid solution, the coating presents lower i corr values in polarization curves and higher fitted R f values in EIS plots than that of as-cast 304 stainless steel.

Devitrification of arc-sprayed FeBSiNb amorphous coatings: Effects on wear resistance and mechanical behavior

Abstract: FeBSiNb amorphous coatings were synthesized by arc spray processing The effects of annealing treatments on the microstructure, elastic and mechanical properties of the coatings were investigated Annealing below 650 °C induces the formation of α-Fe phase nanocrystals Annealing at 650 °C promotes the formation of Fe 3 B, Fe 23 B 6 phases and α-Fe solid solution The as-sprayed coating displays ultra-high hardness ( H > 16 GPa), high reduced Young's modulus ( E r > 210 GPa) and good wear resistance These properties are further improved after annealing treatments ( H > 20 GPa and E r > 260 GPa are achieved in the fully crystallized coating) The mechanical hardening is accompanied with an increase of the ratio of hardness to elastic modulus ( H / E r ), the yield pressure ( H 3 / E r 2 ) and the elastic recovery ( η value) The different microstructural mechanisms responsible for these annealing-induced changes in mechanical and elastic properties are discussed

Characterization of mechanical properties of FeCrBSiMnNbY metallic glass coatings

Abstract: This article investigates mechanical characteristics of Fe-based metallic glass coatings. A series of the coatings were fabricated by conventional wire-arc spray process. The microstructure of the coating was characterized by means of X-ray diffraction, scanning election microscopy equipped with energy dispersive X-ray analysis, transmission electron microscopy, and differential scanning calorimeter. The coating is very dense smooth, adhering well and with no cracking. The microstructure of the coating consists of amorphous phase and α(Fe,Cr) nanocrystalline phase. The nanocrystalline grains with a size of 30 to 60 nm are homogenously dispersed in the amorphous phase matrix. The crystallization temperature of the amorphous phase is about 545 °C. The mechanical properties, such as porosity, adhesive strength, microhardness, elastic modulus, and abrasive wear resistance, were analyzed in detail. The experimental results indicate that the coating has high microhardness (15.74 GPa), high elastic modulus (216.97 GPa), and low porosity (1.7%). The average adhesive strength value of the coating is 53.6 MPa. The relationship between abrasive wear behavior and structure of the coating is discussed. The relatively wear resistance of metallic glass coating is about 7 and 2.3 times higher than that of AISI 1045 steel and 3Cr13 martensite stainless steel coating, respectively. The main failure mechanism of metallic glass coating is brittle failure and fracture. The Fe-based metallic glass coating has excellent wear resistance.

High-Entropy Alloys Fundamentals and Applications

Abstract: Alloys have evolved from simple to complex compositions depending on the ability of mankind to develop the materials. The resulting improved functions and performances of alloys enable advancements in civilizations. In the last century, significant evolution and progress have led to the invention of special alloys, such as stainless steels, high-speed steels, and superalloys. Although alloys composed of multiple elements have higher mixing entropy than pure metals, the improved properties are mostly due to mixing enthalpy that allows the addition of suitable alloying elements to increase the strength and improve physical and/or chemical properties. Since the turn of the century, more complex compositions with higher mixing entropies have been introduced. Such complex compositions do not necessarily guarantee a complex structure and microstructure, or the accompanied brittleness. Conversely, significantly higher mixing entropy from complex compositions could simplify the structure and microstructure and impart attractive properties to the alloys. Jien-Wei Yeh and Brian Cantor independently announced the feasibility of high-entropy alloys and equi-atomic multicomponent alloys in reports published in 2004. This breakthrough in alloying concepts has accelerated research on these new materials throughout the world over the last decade.

Corrosion-Resistant High-Entropy Alloys: A Review

Abstract: Corrosion destroys more than three percent of the world’s gross domestic product. Therefore, the design of highly corrosion-resistant materials is urgently needed. By breaking the classical alloy-design philosophy, high-entropy alloys (HEAs) possess unique microstructures, which are solid solutions with random arrangements of multiple elements. The particular locally-disordered chemical environment is expected to lead to unique corrosion-resistant properties. In this review, the studies of the corrosion-resistant HEAs during the last decade are summarized. The corrosion-resistant properties of HEAs in various aqueous environments and the corrosion behavior of HEA coatings are presented. The effects of environments, alloying elements, and processing methods on the corrosion resistance are analyzed in detail. Furthermore, the possible directions of future work regarding the corrosion behavior of HEAs are suggested.

Microstructures and properties of high-entropy alloy films and coatings: a review

Abstract: In the past 14 years, as a branch of high-entropy alloy (HEA) materials, HEA films and coatings have exhibited the attractive and unique properties, relative to the conventional film and coating ma...