Degradation Rate Of Magnesium Alloy Research Articles

Study on the mechanism of magnesium calcium alloys/mineralized collagen composites mediating macrophage polarization to promote bone repair

Magnesium-based composites are a focal point in biomaterials research. However, the rapid degradation rate of magnesium alloys does not align with the healing time of bone tissue. Additionally, the host reaction caused by magnesium implantation hampers its full osteogenic potential. To maintain an appropriate microenvironment, it is important to enhance both corrosion resistance and osteogenic activity of the magnesium matrix. In this study, a composite scaffold composed of mineralized collagen and magnesium alloy was utilized to investigate the regulatory effect of mineralized collagen on mouse macrophages and evaluate its impact on mouse bone marrow mesenchymal stem cells in terms of osteogenesis, immune response, and macrophage-induced osteogenic differentiation. This experiment examined the biocompatibility of mouse bone marrow mesenchymal stem cells and macrophage-induced osteogenic differentiation in vitro, and examined the expression levels of relevant pathways proteins. Magnesium calcium alloys/mineralized collagen exhibited extensive spreading, facilitated by broad and abundant pseudopodia that firmly adhered them to the material surface and promoted growth and pseudopodia formation. The findings revealed that magnesium calcium alloy/mineralized collagen scaffold materials induced osteogenic differentiation mainly through M2 polarization of macrophages. This effect was mainly mediated by promoting the integrin α2β1-FAK-ERK1/2 signaling pathways and inhibiting the RANK signaling pathways.

Development and Future Trends of Protective Strategies for Magnesium Alloy Vascular Stents.

Magnesium alloy stents have been extensively studied in the field of biodegradable metal stents due to their exceptional biocompatibility, biodegradability and excellent biomechanical properties. Nevertheless, the specific in vivo service environment causes magnesium alloy stents to degrade rapidly and fail to provide sufficient support for a certain time. Compared to previous reviews, this paper focuses on presenting an overview of the development history, the key issues, mechanistic analysis, traditional protection strategies and new directions and protection strategies for magnesium alloy stents. Alloying, optimizing stent design and preparing coatings have improved the corrosion resistance of magnesium alloy stents. Based on the corrosion mechanism of magnesium alloy stents, as well as their deformation during use and environmental characteristics, we present some novel strategies aimed at reducing the degradation rate of magnesium alloys and enhancing the comprehensive performance of magnesium alloy stents. These strategies include adapting coatings for the deformation of the stents, preparing rapid endothelialization coatings to enhance the service environment of the stents, and constructing coatings with self-healing functions. It is hoped that this review can help readers understand the development of magnesium alloy cardiovascular stents and solve the problems related to magnesium alloy stents in clinical applications at the early implantation stage.

Bio-Resorption Control of Magnesium Alloy AZ31 Coated with High and Low Molecular Weight Polyethylene Oxide (PEO) Hydrogels.

Magnesium AZ31 alloy has been chosen as bio-resorbable temporary prosthetic implants to investigate the degradation processes in a simulating body fluid (SBF) of the bare metal and the ones coated with low and high-molecular-weight PEO hydrogels. Hydrogel coatings are proposed to control the bioresorption rate of AZ31 alloy. The alloy was preliminary hydrothermally treated to form a magnesium hydroxide layer. 2 mm discs were used in bioresorption tests. Scanning electron microscopy was used to characterize the surface morphology of the hydrothermally treated and PEO-coated magnesium alloy surfaces. The variation of pH and the mass of Mg2+ ions present in the SBF corroding medium have been monitored for 15 days. Corrosion current densities (Icorr) and corrosion potentials (Ecorr) were evaluated from potentiodynamic polarisation tests on the samples exposed to the SBF solution. Kinetics of cumulative Mg ions mass released in the corroding solution have been evaluated regarding cations diffusion and mass transport parameters. The initial corrosion rates for the H- and L-Mw PEO-coated specimens were similar (0.95 ± 0.12 and 1.82 ± 0.52 mg/cm2day, respectively) and almost 4 to 5 times slower than that of the uncoated system (6.08 mg/cm2day). Results showed that the highly swollen PEO hydrogel coatings may extend into the bulk solution, protecting the coated metal and efficiently controlling the degradation rate of magnesium alloys. These findings focus more research effort on investigating such systems as tunable bioresorbable prosthetic materials providing idoneous environments to support cells and bone tissue repair.

The effects of electrodeposition temperature on morphology and corrosion resistance of calcium phosphorus coatings on magnesium alloy: comparative experimental and molecular dynamics simulation studies.

In this study, CaP coatings were prepared on the surface of an AZ31B magnesium alloy using electroplating in order to slow down the degradation rate of magnesium alloy in the simulated physiological environment. The effect of plating temperature on the properties of CaP coatings was investigated by combining experimental techniques with molecular dynamics (MD) simulation. The surface morphology of CaP coatings changed from dendritic lamellar to granular structure with the increase of plating temperature, but the main structure of CaP coatings prepared at all temperatures was CaHPO4·2H2O. The CaP coatings prepared at 60 °C have higher corrosion resistance compared to coatings prepared at other temperatures. The MD simulation revealed the DCPD/Mg interfacial binding mechanism, and DCPD/Mg could form a stable interfacial layer at different temperatures because the binding energy was negative. HPO42- and H2O groups in the DCPD structure acted as riveting groups in the interfacial layer and formed Mg-HPO42- and Mg-H2O dipole pairs with Mg respectively through electrostatic interaction and van der Waals forces. The interfacial bonding energy between DCPD/Mg reached its lowest at 60 °C and the relative contents of HPO42- and H2O in the interface layer were the highest at this temperature, which may explain the high corrosion resistance and high bonding force of CaP coatings prepared at this temperature.

Improved corrosion resistance and biocompatibility of AZ31 alloy by acid pickling pretreatment and (H+) hydroxyapatite/chitosan composite coating

As a new generation of biodegradable hard tissue repair implants, the excessive corrosion rate in a liquid environment and the potential cytotoxicity of magnesium and its alloys have limited their further clinical applications to some extent. Because of this, in this study, a network-like porous structural surface with relatively uniform pore size was designed and prepared on the surface of AZ31 magnesium alloy by acid etching treatment, and the HAp prepared on this surface exhibited the advantage of high interfacial bonding strength, and the (H+)HAp /CS composite coating was prepared by using biocompatible CS as the sealing layer of the HAp coating pores, and the acid etching was investigated by electrochemical tests. The corrosion resistance of HAp prepared under acid-etching conditions and HAp prepared on AZ31 surface without acid-pickling treatment were investigated by electrochemical tests, while the composite coatings were characterized by X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and EDS, and further tests such as electrochemical experiments, hydrogen precipitation experiments and cytocompatibility assessment concluded that the composite coating has good corrosion resistance, can effectively reduce the degradation rate of magnesium alloy, low magnesium ion precipitation concentration in the cell culture process has less effect on cell growth, and the coating can promote the attachment and proliferation of BMSCs osteoblasts, showing excellent cytocompatibility. Therefore, this study provides a new idea for the design of AZ31 surface morphology and the improvement of corrosion resistance and biocompatibility of AZ31 magnesium alloy, which is beneficial to promote the further development of AZ31 magnesium alloy as a bone repair material.

Enhanced corrosion resistance and biocompatibility of an elastic poly (butyleneadipate-co-terephthalate) composite coating for AZ31 magnesium alloy vascular stents

Surface modification has been considered to provide an effective solution to the poor corrosion resistance of magnesium alloys. A large number of relevant studies have demonstrated that various protective coatings can reduce the degradation rate of magnesium alloys, but most of them are for magnesium alloy materials and devices without deformation. For biodegradable magnesium alloy stents, the selection of protective coating is vitally important due to the residual stress during implantation and cyclic loading after implantation. Therefore, compared with commonly used poly-D,l-lactide (PDLLA), a reliable protection was proposed on HF-treated Mg alloy via application of poly(butyleneadipate-co-terephthalate) (PBAT) with high elongation at break in this paper. In the long term, the corrosion resistance of PBAT-F coating of both flake samples and stents was decisively superior to PDLLA, which could be attributed to its outstanding barrier performance and mechanical properties. Simultaneously, PBAT composite coating exhibited better hemocompatibility and higher cell proliferation rates. The above results show that PBAT is an excellent coating material for vascular stents whereas PBAT composite coating could be a promising candidate as a protective coating for Mg stents.

Bioinspired Surface Design for Magnesium Alloys with Corrosion Resistance

Magnesium alloys are regarded as potential candidates in industrial and biomedical applications because of their excellent mechanical properties and biodegradability. However, the excessive degradation rate of magnesium alloys can cause a premature disintegration of mechanical integrity, which is the main bottleneck that limits applications. Inspired by nature, various novel surface designs provide a clever strategy to regulate the corrosion behavior of magnesium alloys. This review extensively discusses bioinspired surface designs to reduce corrosion resistance and realize functionalization, so as to offer new ideas with great potential for biomedical applications. Future research on corrosion resistance is expected to benefit greatly from the bioinspired surface designs.

Surface Modification of WE43 Magnesium Alloys with Dopamine Hydrochloride Modified GelMA Coatings

As biodegradable medical implants, magnesium alloys have attracted great concerns due to their desirable biological and mechanical performances. Nevertheless, the overfast degradation rate of magnesium alloys makes it difficult to make full use of their potential in medical sciences. Therefore, it is a hot issue to control the degradation rate and functionalize the magnesium alloys via surface modifications. Herein, methacrylate gelatin (GelMA) hydrogel was adopted as coatings on the surface of WE43 magnesium alloys to control the degradation behaviors of magnesium alloys. Inspired by mussels, dopamine (DOPA) hydrochloride was adopted to modify GelMA to further functionalize the coatings. The compositions, swelling properties, degradation behaviors, and morphologies of samples were characterized by UV-Vis spectrophotometer, nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), and immersion test. It was shown that GelMA-DOPA composites could be obtained and the swelling and degradation behaviors of magnesium alloys could be controlled by adjusting the compositions of GelMA and DOPA. Furthermore, the GelMA-DOPA hydrogel coatings can be tightly bonded to the Mg alloys.

Advances in degradation behavior of biomedical magnesium alloys: A review

Magnesium alloys have become promising biomedical metal materials because of their biocompatibility, degradability, and good mechanical properties. However, the rapid degradation of magnesium alloys and its associated effects have limited the applications of magnesium alloys. Alloying and preparation processes can reduce the degradation rate by changing the microstructure of magnesium alloys, such as grain size, porosity, formation of intermetallic compounds/second phases, etc. In this paper, the in vitro and in vivo degradation of magnesium alloys were reviewed in terms of degradation mechanism, influencing factors, and corrosion products. Composition design and manufacturing process were mainly discussed for controlling the degradation, and surface treatment and structural design were briefly described as control methods of degradation. This helps achieve the goal of controlled and predictable degradation rate of magnesium alloys.

Improving the corrosion behavior of magnesium alloys with a focus on AZ91 Mg alloy intended for biomedical application by microstructure modification and coating.

Magnesium alloys such as AZ91 have received much attention due to their attractive properties, including biocompatibility and lightness. Although magnesium is a potential candidate for implant application, due to its rapid degradation in the physiological environment, there are still some challenges to using it as biocompatible implants. In this regard, various techniques such as microstructure modification and coating are utilized to moderate the degradation rate of magnesium alloys. Therefore, efforts are being made to conduct more extensive research to produce magnesium implants with acceptable corrosion resistance. In this literature review, an overview of the history of research on the corrosion behavior, biodegradability, microstructure deformation mechanisms, crystallographic texture in magnesium alloys with a focus on AZ91 Mg alloy, is provided. In addition, the necessity of improving the properties of AZ91 Mg alloy by the two methods of improving microstructure and coating, and existing innovations in these methods are investigated.

Experimental And Numerical Investigation Of Large Strain Extrusion Machining Of AZ31 Magnesium Alloy For Biomedical Applications

Magnesium alloys represent promising bioresorbable orthopedic materials thanks to their biocompatibility, non-toxicity, and mechanical properties that are pretty close to the ones of the human bone. Nevertheless, the major drawback that impairs their widespread adoption in the biomedical field is represented by their unsatisfactory corrosion resistance once placed in the human body environment. Several research studies have demonstrated that an effective method to control the degradation rate of magnesium alloys is represented by a proper conditioning of the surface characteristics of the alloy. With this in mind, the present work proves the feasibility of using Large-Strain Extrusion Machining (LSEM), namely a hybrid cutting-extrusion process, as a strategy to sensibly affect the surface features of the AZ31 magnesium alloy, and, as a consequence, its corrosion performances. The microstructure and micro-hardness close to the machined surface was investigated after LSEM. The experimental results were exploited to develop, calibrate and validate numerical simulations able to describe the microstructural and mechanical phenomena that occur under LSEM. The proposed approach shows that the simulation model can represent a useful tool to predict the magnesium alloy machining performances, thus reducing the need for numerous and time-consuming experimental tests to a great extent.

Bioresorption Control and Biological Response of Magnesium Alloy AZ31 Coated with Poly-β-Hydroxybutyrate

Magnesium and its alloys are not normally used as bioresorbable temporary implants due to their high and uncontrolled degradation rate in a physiological liquid environment. The improvement of corrosion resistance to simulated body fluids (SBF) of a magnesium alloy (AZ31) coated with poly-β-hydroxybutyrate (PHB) was investigated. Scanning electron microscopy, Fourier transform infrared spectrometer, and contact angle measurements were used to characterize surface morphology, material composition, and wettability, respectively. pH modification of the SBF corroding medium, mass of Mg2+ ions released, weight loss of the samples exposed to the SBF solution, and electrochemical experiments were used to describe the corrosion process and its kinetics. The material’s biocompatibility was described by evaluating the effect of corrosion by products collected in the SBF equilibrating solution on hemolysis ratio, cytotoxicity, nitric oxide (NO), and total antioxidant capacity (T-AOC). The results showed that the PHB coating can diffusively control the degradation rate of magnesium alloy, improving its biocompatibility: the hemolysis rate of materials was lower than 5%, while in vitro human umbilical vein endothelial cell (HUVEC) compatibility experiments showed that PHB-coated Mg alloy promoted cell proliferation and had no effect on the NO content and that the T-AOC was enhanced compared with the normal group and bare AZ31 alloy. PHB-coated AZ31 magnesium alloy extraction fluids have a less toxic behavior due to the lower concentration of corrosion byproducts deriving from the diffusion control exerted by the PHB coating films both from the metal surface to the solution and vice versa. These findings provide more reference value for the selection of such systems as tunable bioresorbable prosthetic materials.

Research advances in magnesium and magnesium alloys worldwide in 2020

Research on magnesium alloys continues to attract great attention, with more than 3000 papers on magnesium and magnesium alloys published and indexed in SCI in 2020 alone. The results of bibliometric analyses show that microstructure control and mechanical properties of Mg alloys are continuously the main research focus, and the corrosion and protection of Mg alloys are still widely concerned. The emerging research hot spots are mainly on functional magnesium materials, such as Mg ion batteries, hydrogen storage Mg materials, and bio-magnesium alloys. Great contributions to the research and development of magnesium alloys in 2020 have been made by Chongqing University, Chinese Academy of Sciences, Central South University, Shanghai Jiaotong University, Northeastern University, Helmholtz Zentrum Geesthacht, etc. The directions for future research are suggested, including: 1) the synergistic control of microstructures to achieve high-performance magnesium alloys with concurrent high strength and superior plasticity along with high corrosion resistance and low cost; 2) further development of functional magnesium materials such as Mg batteries, hydrogen storage Mg materials, structural-functional materials and bio-magnesium materials; 3) studies on the effective corrosion protection and control of degradation rate of magnesium alloys; 4) further improvement of advanced processing technology on Mg alloys.

In vivo and in simulated body fluid degradation behavior and biocompatibility evaluation of anodic oxidation-silane-chitosan-coated Mg-4.0Zn-0.8Sr alloy for bone application

With the development and progress of science and technology, magnesium and magnesium alloys have attracted more and more researchers' attention because of their excellent biocompatibility. However, rapid degradation rate of magnesium alloy in vivo seriously limits its application (Arthanari et al., n.d.; Cui et al., 2013 [1,2]). In order to solve this problem, the surface modification of Mg-4.0Zn-0.8Sr alloy was adopted in this paper. According to the requirements of orthopedic materials, anodizing coating (AO), silane coating (SA) and chitosan coating (CS) coating were prepared on its surface, and magnesium alloy was prepared into intramedullary nail, and the corrosion resistance and biocompatibility of the corresponding samples was evaluated. The experimental results show that the AO-SA-CS coating sample has higher corrosion resistance, in addition, it also shows good biocompatibility, such as lower hemolysis rate and normal platelet adhesion morphology. After implantation into the femur, the femur of rats recovered well and the kidney tissue was normal.

Enhanced mechanical properties and degradation rate of Mg–Ni–Y alloy by introducing LPSO phase for degradable fracturing ball applications

Abstract In this work, as-cast Mg–Ni–Y alloys were proposed to develop a feasible material for fracturing balls, and their mechanical performance and corrosion behavior were systematically investigated. Long period stacking order (LPSO) phase was firstly introduced to improve both the mechanical properties and degradation rate of magnesium alloys. With the increase of LPSO phase, the compressive strength was improved significantly, while the elongation of the alloys decreased owing to the relatively brittle nature of LPSO phase. Due to the higher corrosion potential of LPSO phase, the LPSO phase can accelerate the corrosion process by providing more micro-couples. However, the LPSO phase would serve as the corrosion barrier between the corrosion medium and the matrix when the contents of LPSO phase are too high in Mg92.5Ni3Y4.5 and Mg87.5Ni5Y7.5 alloys. As-cast Mg97.5Ni1Y1.5 alloy with satisfactory mechanical properties and rapid degradation rate was successfully developed, exhibiting a high degradation rate of 6675 mm/a (93 °C) in 3 wt.% KCl solution and a favorable ultimate compressive strength of 410 MPa. The degradation rate of Mg97.5Ni1Y1.5 alloy is 2–5 times of the current commercial magnesium alloy fracturing materials.

Surface modification of biodegradable AZ91 magnesium alloy by electrospun polymer nanocomposite: Evaluation of in vitro degradation and cytocompatibility

Magnesium alloys have recently attracted significant attention for the fabrication of biodegradable orthopedic implants and cardiovascular stents. Nevertheless, the high degradation rate of magnesium alloys under physiological conditions is still challenging. We present a surface modification strategy to tailor the degradation rate and in vitro cell behavior of AZ91 alloy through electrospinning of continuous poly (ε-caprolactone) fibers containing bioactive glass nanoparticles (~30 nm). The average thickness of the nanocomposite film and the fibers are 30 μm ± 5 and 300 ± 31 nm, respectively. Electrochemical studies in simulated body fluid and standard immersion corrosion tests have determined that the degradation rate of the magnesium alloy is reduced by two orders of magnitude. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction analyses have shown the formation and precipitation of hydroxyapatite and magnesium hydroxides on the surface of fibrous film after 7 days of incubation. In addition to enhancing the in vitro bioactivity, osteosarcoma and fibroblast cell assays have revealed better cell adhesion and viability on the coated surface. The mechanisms of improved properties are ascribed to the effect of nanocomposite film on the hydrophilicity of the surface and mass transport through the fibrous structure as well as the presence of bioactive nanoparticles.

Effect of Sintering Temperature on Morphology, Mechanical Properties and Degradation Rate of Magnesium Alloy as Biodegradable Material

Mg-alloy has possibility to be used as biodegradable biomaterial. The main problem in application of this material is high degradation rate. The aim of this research is to study the mechanical, morphology and the degradation properties of Mg-alloy biodegradable by variation of sintering temperature of 500 °C, 550 °C, and 600 °C. Morphology was investigated using SEM-EDX. Phase identification was carried out by XRD and mechanical qualities test was measured by compressive and hardness test. Degradation rate test was assessed by weight loss test. The outcomes show that Mg–Zn– Cu sample with sintering temperature 600 °C is the optimum result. The compressive strength is 175,14 MPa, the hardness value is 410,59 MPa, and degradation rate is 8,57 cm/year.

Corrosion behavior of porous ZrO2 ceramic coating on AZ31B magnesium alloy

Magnesium alloys have been recognized as promising implant materials because of their biodegradability. However, rapid degradation due to electrochemical corrosion compromises their cytocompatibility and mechanical integrity. In the present work, a porous ZrO2 ceramic coating was constructed on the surface of AZ31B magnesium alloy (ZrO2-AZ31B) to improve its corrosion resistance. The corrosion resistance of the coating was evaluated in simulated body fluid solution by electrochemical techniques. Higher open circuit potential, impedance and polarization resistance of ZrO2-AZ31B indicate it has a better corrosion resistance than that of AZ31B substrate in simulated body fluid solution. The results suggest that fabricating a ZrO2 ceramic coating on magnesium alloys is an effective method to decrease the degradation rate of magnesium alloys thereby better matching clinical requirements.

Controlling corrosion rate of Magnesium alloy using powder mixed electrical discharge machining

Biomedical implant can be divided into permanent and temporary employment. The duration of a temporary implant applied to children and adult is different due to different bone healing rate among the children and adult. Magnesium and its alloys are compatible for the biodegradable implanting application. Nevertheless, it is difficult to control the degradation rate of magnesium alloy to suit the application on both the children and adult. Powder mixed electrical discharge machining (PM-EDM) method, a modified EDM process, has high capability to improve the EDM process efficiency and machined surface quality. The objective of this paper is to establish a formula to control the degradation rate of magnesium alloy using the PM-EDM method. The different corrosion rate of machined surface is hypothesized to be obtained by having different combinations of PM-EDM operation inputs. PM-EDM experiments are conducted using an opened-loop PM-EDM system and the in-vitro corrosion tests are carried out on the machined surface of each specimen. There are four operation inputs investigated in this study which are zinc powder concentration, peak current, pulse on-time and pulse off-time. The results indicate that zinc powder concentration is significantly affecting the response with 2 g/l of zinc powder concentration obtaining the lowest corrosion rate. The high localized temperature at the cutting zone in spark erosion process causes some of the zinc particles get deposited on the machined surface, hence improving the surface characteristics. The suspended zinc particles in the dielectric fluid have also improve the sparking efficiency and the uniformity of sparks distribution. From the statistical analysis, a formula was developed to control the corrosion rate of magnesium alloy within the range from 0.000183 mm/year to 0.001528 mm/year.

A Pre-Treatment Coating with Redox-Responsive Self-Healing Function for AZ31B Magnesium Alloy

Benefiting the major advantages such as high strength to weight ratio and good formability, magnesium alloy, as a significant light alloy, has shown great potential in modern machine manufacturing field. Unfortunately, limited by their poor corrosion resistance and fast degradation rate, magnesium alloy materials face predicament in stability and durability. Considering that the degradation rate of magnesium alloy is very quick, the repairing speed should also be fast enough to overtake the corrosion process. Hence, sensitive, rapid responsiveness and fast repair process is necessary for magnesium alloy protection. Electrochemical potential was chosen as indicator to monitor the corrosion process: It decreases as soon as the corrosion took place, and it only declined with corrosion reaction. This character guarantees the sensitivity of self-healing coating based on electrochemical potential mechanism to sense the very beginning of corrosion reaction. Disulfide bond unit was frequently introduced into controlled release systems for redox-responsiveness due to that they could easily be reduced and cleaved into thiol groups. Inside human body, there exists abundant glutathione (GSH) in the cytosol. This reducing substance could realize rapid cleavage of disulfide bonds. According to previous literatures, the half-cell potential of GSSG/GSH was -0.26 V, while for magnesium alloy, their corrosion potential is much lower. Therefore, it is expected that the redox reactions during corrosion of magnesium alloy would have the same effect in cleaving disulfide bond as GSH. Following this biomimetic idea, corrosion environment combined with disulfide could realize redox-responsive self-healing agent release, composing the most dependable self-healing mechanism. Herein, we report a sensitive, intelligent anticorrosion sol-gel pre-treatment coating based on redox-responsive motif. As key component, self-healing agent, the inhibitor molecules benzotriazole (BTA) was located inside mesoporous silica materials, sealed by supramolecular complex gate. Composed by novel macrocyclic molecules, water soluble pillar[5]arenes (WP5) and pyridine cation derivative molecules (G), the formation of supramolecular complex is driven by electrostatic force and hydrophobic function. Disulfide bonds were used as linker connecting surface of mesoporous silica nanospheres and the “gate” molecules. To shorten the travel path of inhibitor molecules, we added Fe3O4 nanoparticles inside mesoporous silica layer to fabricate magnetic intelligent nanocontainers. To our knowledge, the magnetic properties have been widely used for controlling the location of materials. Therefore, under the effect of external magnetic field, the magnetic nanocontainer with BTA wrapped inside could be enriched to coating-metal interface. Through shortening the travel path, the inhibitor molecules could reach the corroded areas in minimal time, further accelerating repairing speed. Through evaluations by in-situ scanning kelvin probe technique (SKP), the reported coating exhibit the rapid self-healing functionality, give the timely feedback and maintain the reliable long-term protection of magnesium alloy. 15 μL of 0.05 M NaCl electrolyte was covered on artificial defect (deep into the alloy layer, simulating the coating deterioration at the beginning of corrosion) and NiCr SKP probe was positioned 100μm above the sample surface. Through non-destructive, in-situ measurement of electrode potential at metal surface, a function of the potential over time was recorded (Figure 1B). At the beginning of immersion, the potential at defect site remains level, at the corrosion potential of AZ31B (-1.5 V), indicating that the contact between metal and electrolyte leads to active corrosion in all the samples. After four hours of immersion, the corrosion potential of doped sample rockets to -1.05 V, entering into the passivation range, while for undoped sample, it did not display self-healing function. This is the first time that precise control over location of repair factor inside coatings is achieved. Figure 1