Hard to generalize, But due to lower surface area compared to volume for a sphere, spheoridal microstructure is likely to have higher corrosion resistance compared to dendritic (unless some phase change occurs)

Good day, Qanita Tayyaba! Hope you are doing well.

Generally, under the equal sircumstances, materials with lower surface area (sphere) should have lower corrosion rate per material mass unit, then materials with developed surface (dendrites, fibers etc.). Lower surface area results decreased interactions with corrosive agents.

Feel free to mention me in your response in case of any extra questions.

Best of luck in your research!

Yours sincerely,

M. Sc. Vadym Chibrikov

Department of Microstructure and Mechanics of Biomaterials

Institute of Agrophysics, Polish Academy of Sciences

Additionally to the comments of M. Bhowmick and Chibrikov which seems to me me quite pertinent, I wished to mention the fact that the dendritic solidification mode present also one main drawback when it comes to corrosion behaviour : the propension of segregation into inter-dendritic spaces who is well known to favourize local corrosion problems.

Spherodical. Is more excellent in corrosion resistant

I agree that spheroidal is more corrosion-resistant than dendritic cast structure.

Hi

the Atomic Segregation Propensity is much higher for dendritic structures when compared to spherical particles (aiding corrosion)and inversely related to surface area(minimising corrosion).

thanks & regards,

g.sudhakar

phd(materials engineering)

hcu.

Thank you everyone for adding valuable comments.

Dendritic structure has less corrosion resistance compare to spheroidal structure due to dendritic structure is more metastable. However ,as grain boundary cohesion force of dentritic structure is high grain boundary will be less visible.

For WHAT mode of corrosion: General?, pitting? galvanic? erosion-corrosion, automobile corrosion? Under-deposit corrosion? MIC? Filiform? etc?

I would expect Spheroidal microstructure is more corrosion resistant than dendritic microstructure. The former has gone through an orderly heat treatment whereas the latter is as cast structure. That is why.

Suppose a non spherical phase(p 1) is developed in to another phase(p2) (case 1) and for case 2, a spherical phase(p1) is developed in to another phase(p2). Then of course for case 1, there have higher probability for corrosion compare to case 2 because for case 1 there have higher surface area to volume ratio compare to case 2. This is the only reason considering all other factors are same for these two case.

This article discusses metal used for medical tools and adds mitigating conditions. "Microstructure, Microhardness, Corrosion Resistance and Chemical Composition of Mo, B and Mo-B Coatings Produced Using Laser Processing" at this link

Article Microstructure, Microhardness, Corrosion Resistance and Chem...

The dendritic structure has less corrosion resistance compared to spheroidal structure due to the dendritic structure being more metastable. However, as the grain boundary cohesion force of the dendritic structure is high, the grain boundary will be less visible.

In welding austenic CrNi-steels sometimes a closed dendritic structure is formed by the „deltaferrite“ resulting in the so called ferrite path corrosion.

c.f. Riedl, R.: An Extraordinary Case of Corrosion. Practical Metallography

https://doi.org/10.1515/pm-1990-271006