Shuaishuai Zhu

Bio: Shuaishuai Zhu is an academic researcher from Hohai University. The author has contributed to research in topics: Thermal spraying & Corrosion. The author has an hindex of 2, co-authored 3 publications receiving 9 citations. Previous affiliations of Shuaishuai Zhu include Nanjing Institute of Technology.

Ultrasonic cavitation erosion behaviors of high-velocity oxygen-fuel (HVOF) sprayed AlCoCrFeNi high-entropy alloy coating in different solutions

Abstract: In this study, an AlCoCrFeNi high-entropy alloy (HEA) coating was fabricated by HVOF spraying process. The HEA coating was consisted of the BCC phase (Al-rich phase) and FCC phase (Al-poor phase). The BCC phase was main phase. The mechanical performances and corrosion resistances of the coating and 06Cr13Ni5Mo martensitic stainless steel were analyzed in detail. The cavitation erosion behaviors and mechanisms of the HEA coating and 06Cr13Ni5Mo steel were investigated in distilled water and 3.5 wt% NaCl solution. The effects of microstructures, mechanical properties and corrosion properties on cavitation erosion mechanisms were discussed through the observation of eroded surface morphologies. The results showed that the cavitation erosion resistance of the AlCoCrFeNi coating was about 3.5 times that of the 06Cr13Ni5Mo steel in both solutions. In the 3.5 wt% NaCl solution, corrosion damage aggravated cavitation erosion damage, although the enhancement effect of corrosion on cavitation was limited. The corrosion environment did not change the cavitation erosion mechanisms of the two materials. The cavitation erosion mechanism of the HEA coating was lamellar spalling caused by the extension of the interlaminar cracks. Due to the lower plastic deformation resistance, the cavitation erosion mechanism of the 06Cr13Ni5Mo steel was material spalling caused by plastic deformation and fatigue fracture.

Effect of WC-10Co on cavitation erosion behaviors of AlCoCrFeNi coatings prepared by HVOF spraying

Abstract: The (AlCoCrFeNi)1-X(WC-10Co)X composite coatings were fabricated by HVOF spraying and their microstructures, mechanical properties and cavitation erosion behaviors were tested. The effects of WC-10Co on the cavitation erosion mechanisms were discussed by compared the differences of volume losses and eroded surface morphologies between the coatings. The cavitation erosion resistance of the coatings was about 3 times as that of the 06Cr13Ni5Mo steel. With the addition of WC-10Co, the cavitation erosion resistance of the coating was slightly increased. In the initial stage of cavitation erosion test, the cavitation erosion damage was concentrated on the interface, which was caused by the uncoordinated deformation and poor mechanical properties of the interface between HEA and WC-10Co. When the WC-10Co distributed below the HEA region, the WC-10Co played a strong supporting role and improved the impact resistance of the HEA region. The cavitation erosion mechanism of the HEA1 coating was lamellar spalling. The cavitation erosion mechanisms of the HEA2 and HEA3 coatings were particles spalling and lamellar spalling.

Electrochemical properties and cavitation erosion behaviors of HVOF sprayed (AlCoCrFeNi)1-X(WC-10Co)X composite coatings in NaCl medium

Abstract: The (AlCoCrFeNi)1-X (WC-10Co)X composite coatings were fabricated on 06Cr13Ni5Mo steel by high-velocity oxygen-fuel (HVOF) spraying. The coatings' microstructure, mechanical properties, and corrosion performance were characterized, and the cavitation erosion resistance of the coatings was tested in 3.5 wt% NaCl medium. The influence of the microstructure, mechanical properties, and corrosion resistance on cavitation erosion resistance were discussed. The microhardness and local plastic deformation resistance of the coatings were increased by WC-10Co, while the corrosion resistance of the composite coatings was decreased by severe galvanic corrosion. The cavitation erosion mechanism of the coatings was lamellar spalling. In NaCl medium, the (AlCoCrFeNi)75(WC–10Co)25 (HEA75/WC25) coating showed lower cavitation erosion resistance than the AlCoCrFeNi (HEA) coating, which was caused by the galvanic corrosion, uncoordinated deformation and the low bonding strength of the HEA/WC-10Co interface. For the HEA75/WC25 coating and (AlCoCrFeNi)50(WC–10Co)50 (HEA50/WC50) coating, the cavitation erosion damage of the HEA75/WC25 coating was higher than that of the HEA50/WC50 coating. When the microstructure and corrosion resistance of the coatings were similar, the cavitation erosion resistance was mainly affected by the mechanical property.

A review on laser cladding of high-entropy alloys, their recent trends and potential applications

Abstract: High-Entropy Alloys (HEAs) are a promising class of metallic materials that have allured the world of material science and engineering. These intriguing materials are proving their worth in the coatings for severe ambient and demanding conditions. Laser cladding (LC) is a non-linear complex, multidisciplinary and modern technology applied for surface modification. Nobler properties of HEAs as compared to traditional alloys permitted the research community to explore Laser-Cladded High-Entropy Alloy Coatings (LC-HEACs). Here, this article provides a review and recent trends of LC-HEACs, aiming to address the use of LC technology for HEA materials, the influence of process parameters on the geometric and metallurgical characteristics of the LC-HEACs. Common defects not limited to microcracks and residual stresses, and techniques to improve the quality of the LC-HEACs are elucidated. Furthermore, thermo-kinetics effect, thermomechanical behavior, microstructural evolution, and strengthening mechanisms are illustrated for a better understanding of laser-material interaction. The potential applications of the LC-HEACs are outlined considering wear, corrosion, erosion, and oxidation resistance and their corresponding substrates. The article also highlights the research gaps, current trends, and possible future directions in the context of critical challenges that need to be catered, before the actual implementation of LC-HEACs in industries. Owing to the variety of element constitution for HEAs design as well as excellent mechanical and functional properties, LC-HEACs will blossom in the years to come.

Effects of heat treatment on the microstructure, mechanical properties and corrosion resistance of AlCoCrFeNiTi0.5 high-entropy alloy

Abstract: AlCoCrFeNiTi0.5 high-entropy alloy was fabricated, and the effects of heat treatment on the microstructure, mechanical properties and corrosion resistance of this alloy were investigated. The results indicate that heat treatment can not only refine as-cast dendrites and change the morphology of precipitation from long strip to short rod-like structure but also control the ratio of BCC to FCC. The volume fraction of the BCC phase at 1100 °C is 34.8%, which is 9.2% higher than that under the as-cast conditions (25.6%). The highest compression fracture strength and fracture strain of 2785 MPa and 30.7%, respectively, are achieved when the heat treatment temperature and time are 1100 °C and 6 h, respectively. The highest Vickers hardness values of FCC and BCC are 687 HV0.5 and 782 HV0.5, respectively. The order of corrosion resistance is 800-2 h 900-2 h, as-cast, 1000-2 h, 1100-2 h, and 1200-2 h, which is contrary to the trend of the BCC volume fraction. The potential of dendritic FCC is higher than that of interdendritic BCC, and the potential difference is rising because of dendrite decomposition and atom diffusion. The corrosion mechanism is also discussed in this study. Corrosion occurs preferentially on the phase interface and interdendrites, and subsequently connects with each other. As the corrosion intensifies, dendritic FCC begins to be corroded and develops into a large corrosion area.

Laser surface alloying of FeCoCrAlNiTi high entropy alloy composite coatings reinforced with TiC on 304 stainless steel to enhance wear behavior

Abstract: FeCoCrAlNiTi + x%TiC (x = 10 and 30) high entropy alloy (HEA) composite coatings were deposited by laser surface alloying (LSA), aiming at studying the influence of TiC addition on wear resistance. The formed phases, microstructural evolution, hardness and wear behavior of the HEA composite coatings before and after 10-h anneal at 700 °C were clarified in detail by using XRD, SEM, EDS, Vickers hardness measurement and linearly reciprocating friction-wear measurement. The results displayed that three-phase FCC + BCC + TiC was appeared for HEA composite coatings with x = 10 and 30. The formed phases for the HEA coatings with x = 10 and 30 remained unchanged after 10-h annealing at 700 °C. The coatings exhibited dense microstructures, in addition to a good metallurgical bonding to the substrate. TiC particles displayed relatively homogeneous distribution in the matrix for HEA composite coatings with x = 10 and 30. The grains of the HEA matrix were obviously refined due to the TiC particles addition. The nano-hardness (H), nano-hardness/elastic modulus (H/E) and (H3/E2) of HEA composite coatings was obviously increased with the addition of TiC and the HEA composite coatings with x = 30 showed the highest nano-hardness, the ratio of H/E and H3/E2, possessing high resistance to plastic deformation. With the increase in nano-hardness, the specific wear rate of the HEA composite coatings with x = 30 was the lowest with the value of 2.636 × 10−5 mm3/N m, indicating that it possessed the highest wear resistance. In addition, the HEA composite coatings in the current study also displayed an enhanced wear performance compared to the monotonous FeCoCrAlNiTi HEA coating reported in previous work.

Effects of heat treatment on the microstructure, wear behavior and corrosion resistance of AlCoCrFeNiSi high-entropy alloy

Abstract: The effects of heat treatment on the microstructure, wear behavior and corrosion resistance of AlCoCrFeNiSi high-entropy alloy were investigated. Results indicate that the phase composition of as-cast alloy includes disordered body-centered cubic (BCC) solid solution phase, ordered BCC phase (B2), Cr3Si and (Cr, Ni, Si)-phase. The system exhibits a good thermal stability and no phase transition occurs after heat treatment except the change of diffraction peak intensity and the appearance of weak peak. After heat treatment, the dendrites of B2 phase turns into discontinuous spherical particles, the BCC interdendrite region narrows, and the short rod-like precipitation Cr3Si phase is transformed into long needle-like microstructure. The highest compression fracture strength and strain are 1752 MPa and 11.8 % at 1150-2 h, which are 36 % and 19 % higher than the as-cast alloy, respectively. At 1150-2 h, the highest microhardness (1004.3 HV0.5) and lowest friction coefficient (0.115) are obtained, which are 1.2 times and 3.4 times better than that of as-cast alloy. A mixed mechanism of abrasive and oxidative wear are occurred during friction and deformation. Heat treatment of 1100–2 h possesses the optimal corrosion resistance with the Ecorr and Icorr of −330.776 mV and 637.587 nA due to the appearance of weak passivation phenomenon.

Nano- and micro-mechanical properties and corrosion performance of a HVOF sprayed AlCoCrFeNi high-entropy alloy coating

Abstract: In this work, a gas atomized feedstock was used to fabricate an AlCoCrFeNi HEA coating using the high-velocity oxygen fuel (HVOF) process. The coating’s resistance to room temperature surface degradation was evaluated using dry sliding wear and seawater corrosion testing. The coating retained the feedstock phase structure with negligible in-flight oxidation and was composed of a majority BCC phase with a minor B2 phase, resulting in a high micro- and nano-hardness of ~7 GPa. These observed phase compositions were consistent with thermodynamically calculated phase predictions using a CALPHAD model. Microstructure-mechanical property mapping revealed uniform microstructural characteristics. However, the multiscale wear resistance of the coating was critically affected by the presence of the hard BCC/B2 phase composition, which led to severe brittleness. Combinatorial assessment of the worn surface, wear debris and counter body indicated that wear was dictated by a combination of abrasive, surface fatigue, tribo-oxidation and adhesive wear. In addition, the coating exhibited superior general corrosion resistance compared with conventional SS316L, but the selective dissolution of the B2 phase preceded poor localized corrosion resistance, ultimately leading to pitting corrosion.