I recently posted an observation on this question on Why most research use Wrought Alloys when Researching Cast Al-MMC's? Most of papers I see coming to IJMC on Al-MMC's are using wrought as host metal. The common ones are: 6061, 6063, 7045, 7075, and 2000 series. These are very difficult to cast, which is why most of the researchers use very simple shapes just to get test coupons. They also usually conduct only limited mechanical tests and focus on wear testing, which is of limited value to design engineers. These are mostly academic studies and they tend to cite each other's works. I understand trying to limit compositional interactions, but this approach doesn't develop alloys that can be used into useful commercial shapes. The early Al-MMC's were based upon A356 (Al-Si) and also Al-Si-Cu (like 319 and 383) as a means to improve stiffness (modulus) and high temperature properties. There were collaborative efforts to see what material was needed to solve problems and see if it worked.
Prof. Rohatgi gave an AFS Golden Anniversary Lecture in 2019 that was published in the IJMC:
Ajay Kumar, P., Rohatgi, P. & Weiss, D. 50 Years of Foundry-Produced Metal Matrix Composites and Future Opportunities. Inter Metalcast 14, 291–317 (2020). https://doi.org/10.1007/s40962-019-00375-4
See the online version: https://rdcu.be/cB8IH
Unfortunately, this trend of using wrought alloys as the base metal is why a significant number get Transferred to other more materials orientated journals or Open Access. Very few look at can the MMC's developed be cast into complex shapes and can the material be re-processed. This is a BIG PROBLEM!!!! Our universities and researchers must address this issue, if we want to advance the use of materials that can see practical applications. Don't just seek Solutions in Search of a Problem.
Dear Thomas Prucha
If you look at ASM Handbook, Volume 21, Composites, you can see a wide range of cast and wrought aluminum alloys are used as matrix in aluminum MMCs and, if you add the well known figure that about 85% of aluminum is used for wrought products, it makes clear that these wrought alloys have reasonable dominate on the aluminum MMCs research field. Although the cast aluminum alloys yield cost-effective products due its low melting point, they generally have less tensile strengths than wrought alloys and with the best doing reinforcement ,it is not easy to achieves a higher properties than the wrought products properties. For that the academic researchers follow at higher rate the developing research approach of compositing the wrought aluminum alloys products.
Best regards
Dear Thomas,
interesting observation and probably not something metallurgy specific but a general effect in "old technology" subjects.
Bringing together different disciplines such as composites and metallurgy always bring up a certain degree of dilettantism as the two or more groups often do not understand the complementary requirements, that's a general effect. Moreover the basic metalurgy topics such as aluminium cast and wrought alloys are not very fancy topics anymore, they are poorly covered in students teaching. One foundry institute after the other is closed and my impression is that the knowledge gets lost and the effect you mention is created by an increasing deficit of basic understanding.
I am out of the metallurgy business for almost 25 years now and in my current research field which is structural ceramics the situation is very similar. Many researchers do not consider or even know the older works from the 1980s which are often really excellent and prefer to cite to read the latest publications. This is no problem as long as the new publications bring up novel findings. For me as a reviewer for many journals it seems however that this is done regardless of quality.
best regards
Frank
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