measure yield strength

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Ian Armstrong replied on Wed, Jun 3 2015 11:10 AM

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Hi nanoluna,

Both of these quantities would be difficult to measure via AFM because of the discontinuity from macroscale to nanoscale, the level of forces involved, and the design of the instruments that do the traditional testing compared to the AFM.

In principle one could envision looking at yield strength - though, this would be via indentation rather than pulling. In that case we could take a metal film sample and indent it at various loads up to about ~250uN. Re imaging the indentation areas could reveal the load at which plastic deformation is reached. Break strength I think is less feasible given the load range we can impart. Our tribology instruments which include a traditional nanoindenter as well as scratch testers etc... are probably better designed for this sort of experiment. You can take a look at them by copying this link into your browser:

https://www.bruker.com/products/surface-analysis/tribology-and-mechanical-testing.html

Best regards

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nanoluna_1231 replied on Mon, May 9 2016 5:21 AM

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Hello Mr Ian,

I want to enquire you some questions about AFM. Recently, I measure the modulus of metal thin film which  is suspended through Multimode AFM. The red line(retract line) of the force curve is above the red line even though the force is small. Is this normal or if it isn't normal, why? 

In addition, I use the trigger mode to measure the thin film's mechanical feature.If I use the maximun trigger voltage12V ,is the test result still right? I mean, whether  the AFM probe cantilever's stiff is still linear or whether  the diode detector exceed the measuring  range or some other reason when the trigeer voltage is 12V. Then ,what's the appropriate trigger voltage(the maximum acceptable voltage)?

I will  appreciate it for you reply, thanks.

Regards