To my knowledge Zr is used in high strength Al alloys (eg for aircraft components) to act as an anti-recrystallizant during hot working. It forms dispersoids during the homogenisation treatment (so not in the as-cast state) but they do not contribute much to the alloy hardening.

Thank you very much. I have also read about the homogenisation - as the disperosids are formed above 500 Celcius degrees - from the thermodynamical point of view. However, as the casting processes are non equilibrium, I've wondered if some other phenomena may occur. Thank you for the point, that the dispersoids do not contribute to the hardening.

All the best

According to binary Al-Zr phase diagram, the formation of pro-peritectic Al3Zr phase can occur if the Zr level is more than 0.11 wt.%. Then, these particles lead to a peritectic reaction of liquid + Al3Zr = alpha Al. Since the cooling rate is too high and thus there is a limited diffusion in solid-state, the peritectic reaction remains incomplete during solidification. Therefore, Al3Zr particles can be present within alpha Al matrix; however it may not be easy with TEM to reveal them, but with SEM at higher magnifications you may detect them.

Dear Mr Rakhmanov,

Thank you for the information. Why do you think they will be hard to find with TEM? Are they too coarse?

All the best,

Bartek

In my opinion, the fraction of these particles is low. Only a single Al3Zr particle can be present within one alpha Al grain iAdd your answern as-cast state. Therefore, i said it can be hard to detect them by TEM. 

Best regards,

In my opinion, the fraction of these particles is low. Only a single Al3Zr particle can be present within one alpha Al grain in as-cast state. Therefore, i said it can be hard to detect them by TEM. 

Best regards,

I have the same opinion as Jovid Rakhmonov.Since there are the low fraction of these particles it is very hard to prepare specimen for TEM,especially if the particles are not uniformly or they  could be come out.I suggest to use SEM.Sometimes  these particles i saw in LM in as cast state.should be use adequatelly magnifycation and carefully investigate alpha grains,especially inside of the grain or dendrites.I would like to  see some fig. of these microstructure.

Best regards,