During my experiments , I came across decreasing wear rate of Al-Si alloys with increasing Si contents up to near eutectic composition but again it found to increase. But in case of Al- Si-TiB2 wear rate simply decreased even beyond eutectic composition with Si. What are the causes behind it?
you should take care about the following:
1- what are the particle size of both Si& TiB2 ?
2- which of them has a greater hardness?
3- Always Si is very hard and impeded in a matrix of Al
Good Luck
From my understanding Si is very good as antiwear agent but to a certain limit not to exceed 2% from my understanding. Also Ti is a good agent. But to establish a real understanding of all your variables you should build up a matrix and run DOE analysis to optimize your conditions with respect to the materials you are interested in. As I said several variables play a role here even temperature. you should look at your factors interactions and select the best possible concentration
you said (Al-Si ALLOYS) .. what is the aim of your work … before, after, in eutectic point,
Please specify what you are doing exactly so we can target the right response
Thank you all for your valuable responses.
My project is on synthesis and characterization of Al-Si-TiB2 composites.
Si:7 - 18%
TiB2: 2-5%
To find out the response of TiB2 presence on wear of the composites especially in the hypereutectic alloys.
You should take the low and high level of TiB2 and do DOE analysis to check the wear response then you optimize your concentration using ANOVA of factors considered
I think you were prepared the composites by the exothermic reaction of K2TiF6 and KBF4 salts with the molten Al-x Si alloy. did you read (Synthesis and Characterization of TiB2 Reinforced Aluminium Matrix Composites: A Review) or (Wear behavior of Al-Si alloy based metal matrix composite reinforced with TiB2) to extend your view …if you didn't tell me to send it to you best regards
I think the best way is to do some experiments and optimize your results using DOE
"Review of Microstructure Evolution in Hypereutectic Al–Si Alloys and its Effect on Wear Properties "
you may find the answer in this.
Wear characteristics using Si depends on surface and hardness and not on microstructure
But, In Al-Si alloys, the hardness depends on the microstructure , especially, the morphology of silicon has a significant effect on the hardness and other mechanical properties.
Sure silicon is very good for wear and hardness but still more a surface characteristics that provide good resistance at the first 500 microlayers. If you mean the microstructure at these microlayers then I will agree
As the Silicon content is increased it act as stress riser. But if Si is present as intermetallic compound with Mg (as Mg2Si) then it helps in increasing mechanical properties ad wear resistance of the alloy.
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