Study On Corrosion Resistance Of Mg-Nd Alloy

Magnesium alloy is a good performance of alloy materials,which has the advantages of light weight,high than strong strength,good castability,and universal use in the fields of transportation,aerospace,etc.,is considered to be one of the most promising materials.However,the magnesium alloy is still inadequate in mechanical properties and corrosion resistance,which seriously constitutes the scope of application of magnesium alloys,so how to improve the performance of this alloy becomes the focus of people’s research.The neodymium(Nd)element is a rare earth element commonly used in magnesium alloy.In the Mg-Nd binary system,the magnesium alloy containing a small amount of Nd can achieve better precipitation,so that the mechanical properties of the alloy have been significantly improved.At the same time,scientists have also found that Nd elements also have positive effects in improving the corrosion resistance of magnesium alloys.Therefore,it is also very important to develop new Mg-Nd alloys with Nd elements.This paper uses the magnesium binary alloy as a research object,by adjusting the Nd element content,preparing cast Mg-1Nd,Mg-2Nd and Mg-3Nd alloy,by means of soaking test,electrochemical experiment,tissue observation,phase analysis,etc.Systemic Study Mg-Nd dual alloy in a typical marine environment such as sulfucing bacteria,corrosion behavior in a sodium chloride(Na Cl)environment,resulting in corrosion laws under the influence of alloys in SRB and Na Cl media.At the same time,the thermal treatment of the Mg-Nd binary alloy is subject to the object,and the respective microstructure,mechanical properties and corrosion resistance of the solid solution(T4),the solid solution(TE)are studied,thereby determining the different heat treatment processes to magnesium alloy.Resulting effect.The micro-morphology of the cast Mg-Nd binary alloy is a classic dendritic crystal structure,the grain size is large,and the alloy tissue is composed of an alphamg matrix and a second phase(Mg12Nd).After the Nd content is increased from 1% to 3%,the alloy grain refinement,the generated second phase increases,and the second phase also begins from the point,and the short rod-like interrupt discontinuous distribution is gradually distributed to the continuous mesh distribution.Corrosion experiments show that in both SRB and Na Cl,the corrosion rate of the Mg-1Nd alloy added in SRB and Na Cl is the lowest,and the corrosion rate of the Mg-3Nd alloy is the highest,the Mg-2Nd alloy is the highest;with the Nd content Increased,the corrosion speed of the cast Mg-Nd binary alloy in SRB and Na Cl solution decreased,and the corrosion rate of the cast Mg-Nd dubbed binary alloy in the SRB environment was much lower than in the Na Cl medium.The heat treatment will have an important impact on the microstructure and corrosion behavior of the alloy.After the treatment(T4)treatment,the Mg12 Nd phase in the alloy solids into the α-Mg matrix,producing a supersaturated solid solution.After the solid solution(TE)is treated,the Mg12 Nd of the solid solution matrix can re-disperse.In 3.5% Na Cl corrosion medium,the alloy cylinder treatment of solid solution(T4)was lowered,and the solid solution(TE)treatment was the highest,the corrosion rate of the cast(F)alloy was the highest.In the SRB solution,the corrosion rate of the solid-dissolved state and solid solution time is still lower than the cast alloy,but the corrosion rate of solid solubility and solid solution is relatively close.In 3.5% Na Cl corrosion medium,the etching mechanism of the alloy is partial corrosion,mainly manifested as a narrow deep pixel caused by ecpoupic corrosion.The longer the soaking time,the more serious the alloy corrosion,which is mainly because the generated corrosion product is loose and plenty of pit,and cannot be used to protect the alloy matrix.In the SRB solution,the corrosion characteristics of the Mg-Nd dual alloy are local corrosion mainly with a wide-shallow print,which is much densely corrosive than in the sodium chloride solution.Sulfate reduction bacteria can be attached to the surface of the alloy,reproduction and form a complete biofilm.As the soaking time increases,the biofilm is constantly expanding,and the complete biofilm will erode alloy matrix on the one hand,and the other hand can reduce the erosion of the solution,and the alloy is protected to protect the effect.