In addition to Dr. Slipper's answer a simple quantitative phase analysis should also suffice (powder XRD). Ideally, a randomly selected small sample should have the approximate composition to the mixing ratios. Further, the same can also be attempted through EDAX analysis through SEM provided the powders are of different chemical composition.

I hope it helps.

If the mix was accurately weighed and you have taken a representative aliquot then you should be able to use a quantitative Rietveld analysis in order to check the proportions, and therefore the quality of the mix.  The results should be closer to the true values, the better the mixing. I would take repeat samples to check for consistency. Bear in mind that over-grinding can induce structural changes or introduce amorphicity to some materials. So in some cases the results may diverge rather than converge on the correct result!

In addition to Dr. Slipper's answer a simple quantitative phase analysis should also suffice (powder XRD). Ideally, a randomly selected small sample should have the approximate composition to the mixing ratios. Further, the same can also be attempted through EDAX analysis through SEM provided the powders are of different chemical composition.

I hope it helps.

I agreed that the Rietveld analysis on the XRD spectrum of the mixture suffices to justify the composition of the identified phases. EDAX analysis can also provide chemical (both atomic & weight) composition ratio of selected small surfaces of the mixture. Just to clarify, what do you really hope/want (and hence, do you really mean) by 'WELL-MIXED' of the mixture, is it: a) A+B should give a single phase of C?, or b) A+B = the main phase of C + minor phase of D? If a) is the answer and your results still gave C+D phases after varying the length of milling time, then you should re-check the composition of the starting precursor materials, or you should try another appropriate synthesis technique in order to get the desired (or, the well mixed) of C. However, if b) is your hope, and you already got the intended C+D phases, and you want to know the quantitative compositions/ratio for each phase, then do the Rietveld analysis, as suggested by Dr. Slipper. Once you did the Rietveld refinement correctly, whatever the output, the analysis will provide you (molar & weight/mass) ratio of the identified phases that close to the true values. Hope this helps.

It can be depended on the powders. Any milling prcess can't induce phase change in any materials

Actually, I don't want it to change phases. I want it to be A+B as original. But I did milling process just to mix them up. But the problem is, at what time does the mixture mix well? 15min, 2hr / 4hr. If it is not mix well, it will become an issue when I want to do mechanical test after this, (after making this mixture into pellet). Even XRD test shows that it did not change phases at that time.

I wonder that simple milling two powders A & B can induce phase change unless your are doing mechanical alloying. X-ray of mixture will not result in anything. Homogenous mixing depends upon nature of powders, size of balls, duration of mixing etc. Do mixing for various durations and run DTA  and XRD. DTA will give you exact clacination temperature. Calcine samples (mixed with different durations) and then run XRD and EDAX. Take the XRD data which did not show any trace of starting material. You will come to know the homogenity of the mixture of ceramic powder.

I can porpose the confident route:

Mill the pwders to ground fines (for example under 20 micron, it depends to materials and final porpose) separately and then mix them in the same ball mill for another 2hours. You can detect homogenity after calcination with final expected phases

Dear, I'm inclined to increase the grinding time (if the powders are hard), and do a DRX study by Rietveld plus an EDAX of course.

Another possibility is to change the planetary mill for another linear, also used.

Dear my sister Nor, from your answer it is evident that milling time doesn't affect to the XRD data on the identified phases. So, to meet your curiosity, just continue your work by forming green bodies on the mixed powder (pellets) and do mechanical test on it (after sintering it, of course), and compare the performance. I think that's all. All suggestions have been given to you. Good luck!

Dear Nor Rahafza Abdul Manap

Peace be upon you

I think that these short times can not change the phase. The roll milling times should be long more than 6 hrs depending on the grinding components to get considerable phase changes.

I have an experience in this regard. I obtained an amorphous and homogeneous phase from crystalline materials (Cd, S, and Se) but the milling time was 48 hrs continuous.

You can go to my ResearchGate page to see how I prepared the bulk alloy samples from the mechanical milling process.

Regards

Ball-milling normally helps to play on particle size rather than just mixing. All you may get from XRD, if the energy was not high enough to allow mechanical alloying, is the broadening  or sharpening of picks.

Depending on your intended application, for example if you want the components A and B to be not separated in the next step of your experiment (like if you are afraid they may be mechanically separated by difference in density when flowing) the ball-milling is Ok. In that case you can check SEM and EDS if there is formation of particle agglomeration from both components (connected to make bigger quasi-particles. Note that XRD pick bordering may not capture it.

If you intend to use the mixture in an application where the components A and B can not easily be separated again (almost similar density or no powder displacement involved) it could be better to use simpler mixing techniques like blending or agitation.

Good luck!

I agree that the small grinding times used are scarce (as I said in my previous intervention), it would have to estimate the energy that you want to transfer to the powders to modify their grain size in some way, ¿Do you have estimated it?

Ok. Now i understand what to do. Thank you so much for all the brilliant answers. I do appreciate it.

Regards.

You will not be able to see any phase changes by mixing the powders, because you did not change the crystal structure of materials. So, the diffraction pattern will be a composition of the two phases depending on the proportion you mixed them. You may check the proportion using quantitative rietveld analysis.

It depends on the powders and the milling conditions. If the milling conditions are well suited that means Balls to powder ratio BPR and combination of the jars and balls material (YSZ zirconia, steel, or plastic) and then also  if you use high energy ball milling without any dispersant as acetone you can expect the products of the mechanochemical reaction. But, all of that only if the powders are, due to phase diagram, prone to form new phase as a product. Powders can be mixed well, meaning homogenized in a begging first 15 minutes where the size of powder particles is as well reduced. Usually mechanochemical reactions start at 20 minutes and finishes at 120 minutes.  (followed by XRD with 3% error in phase composition).