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•Novel ZK30-xCu alloys are fabricated by selective laser melting (SLM).•SLMed ZK30-xCu alloys have fine grain sizes in microstructure.•SLMed ZK30-xCu alloys have improved ...biodegradation resistance.•SLMed ZK30-xCu alloys have good antibacterial ability and cytocompatibility.
Cu-containing Mg alloys are a novel type of antibacterial biomaterial based on biodegradation of Mg and antibacterial functions of Cu. However, fast degradation limits their clinical application. For the first time, this work utilizes the synergistic effects of biodegradation of ZK30, antibacterial function of Cu and grain refinement by selective laser melting (SLM) to prepare high-performance antibacterial ZK30-Cu alloys. The obtained alloys have an improved biodegradation resistance, which is attributed to remarkable grain refinement by SLM. Furthermore, the alloys exhibit good antibacterial ability and cytocompatibility.
Magnesium (Mg) and its alloys have been widely researched for orthopedic applications recently. Mg alloys have stupendous advantages over the commercially available stainless steel, Co-Cr-Ni alloy ...and titanium implants. Till date, extensive mechanical, in-vitro and in-vivo studies have been done to improve the biomedical performance of Mg alloys through alloying, processing conditions, surface modification etc. This review comprehensively describes the strategies for improving the mechanical and degradation performance of Mg alloys through properly tailoring the composition of alloying elements, reinforcements and processing techniques. It also highlights the status and progress of research in to (i) the selection of nutrient elements for alloying, reinforcement and its effects (ii) type of Mg alloy system (binary, ternary and quaternary) and composites (iii) grain refinement for strengthening through severe plastic deformation techniques. Furthermore it also emphasizes on the importance of Mg composites with regard to hard tissue applications.
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•Equiatomic CoCrFeMnNi HEA was successfully fabricated by selective laser melting.•The composition uniformty and multi-scale microstructure characterization of the SLMed HEA were ...studied.•The SLMed CoCrFeMnNi HEA had better corrosion resistance than the as-cast CoCrFeMnNi HEA in NaCl solution.•The surface three-dimensional profile of the corrosion samples was characterized by laser scanning confocal microscope.
A CoCrFeMnNi high-entropy alloy (HEA) was fabricated by additive manufacturing using selective laser melting (SLM). The corrosion behavior of the SLM-produced and as-cast CoCrFeMnNi HEA in 3.5 wt.% NaCl solution was comparatively analyzed. Compared to the as-cast HEA, more uniform composition and finer grains were observed in the SLMed HEA. The passive film formed on the SLMed HEA had a more stable and stronger protective property. The corrosion current density of the SLMed CoCrFeMnNi HEA dropped by 58 % compared to that of the as-cast HEA, indicating that the SLMed HEA had better corrosion resistance than that of the as-cast alloy.
•Sr–B poisoning effect on Si modification is solved by La addition in Al–10Si alloy.•Ductility of refined Al–10Si–0.05La–0.02B–0.015Sr alloy is twice as La-free alloy.•La reacts with B to form LaB6 ...acting as an effective nucleation site of α-Al.•Multiply twinning of Si is caused by Sr atoms doping at twin boundaries.•Poisoning mechanism of Sr–B are revealed by thermodynamic calculations.
As-cast Al‒Si alloys always face low ductility because of coarse α-Al grains and large lamellar eutectic Si. Although B-containing refiners and Sr modifiers could refine the α-Al grains and eutectic Si respectively, simultaneous addition leads to an invalid effect of Sr because B-containing refiner has a poisoning effect (PE) on Sr modifier in the Al‒10Si‒B‒Sr alloys. The present work achieves both refinement of α-Al grains and modification of Si merely by the addition of 500 ppm La in Al‒10Si‒0.02B‒0.015Sr alloy, which greatly enhances the ductility and tensile strength. Sr‒B interaction in the Al‒10Si‒0.02B‒0.015Sr melt results in a consumption of Sr by forming Sr‒B intermetallic compound. CALPHAD-type calculations reveal that Sr concentration in liquid before eutectic reaction becomes a key parameter to estimate the alloying modification effect. The addition of La forms LaB6 and thereby releases Sr to protect the Sr modification effect. First-principles calculations illustrate that both Sr and La are beneficial to the formation of twin boundaries in Si particles due to their negative formation energy of twin boundaries. The formed LaB6 has a semicoherent interface with α-Al with the orientation relationship of 11¯0LaB6//11¯0Al and (11¯1)LaB6//(11¯1)Al, demonstrating that LaB6 is an efficient nucleation site for α-Al, which contributes to the refinement of α-Al in the Al‒10Si‒0.05La‒0.02B‒0.015Sr alloy. Our findings reveal the micro-mechanism of refinement during the solidification process and develop an effective and simple way to obtain high-performance Al alloys.
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As most of the failures in engineering components initiate from the surface layer, applying surface treatments can play a crucial role in controlling material performance and lifetime. In this study, ...different surface severe plastic deformation techniques including severe shot peening, laser shock peening and ultrasonic nanocrystal surface modification have been considered. The effects of process parameters and the kinetic energy of each treatment on the microstructure, mechanical properties and fatigue behavior of nickel-based super-alloy Inconel 718 have been investigated. The results revealed that using the proper parameters to increase the kinetic energy of the applied surface treatments, it is possible to effectively promote surface grain refinement and induce a deep compressive residual stress field in Inconel 718 samples. Among the applied treatments, ultrasonic nanocrystal surface modification was found to be the most efficient one in improving the mechanical properties as it led to the most significant fatigue performance, followed by severe shot peening and laser shock peening.
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