Hi,

Just have a look on the resent work published by a group from Vienna: 

"Precipitate strengthening of non-spherical precipitates extended in 〈100〉 or {100} direction in fcc crystals" from Ahmadi, M.R. et al. 2014

I think they are working on a strengthening model for beta".

Best regards,

Stefan

Thank you very much.

Milkereit/Kessler  wrote a thesis about that type of hardening by DSC and Mikrohardness. might be interesting for you.

http://www.nt.ntnu.no/users/zebingx/6082%20solution/MSE%20A.pdf

http://rosdok.uni-rostock.de/file/rosdok_disshab_0000000647/rosdok_derivate_0000004617/Dissertation_Milkereit_2011.pdf

best regards

hartwin weber

Dear Rao

I hope you are only looking for the strengthening coming from beta prime precipitates. This gives the maximum hardening within the Aluminium matrix. Experimentally, you can see its effect by observing the selected area diffraction pattern (SAD). The presence of diffraction streaks coming from strain induced by these beta prime precipitates will give you an idea about the presence of these precipitates. In addition, you can also identify its effect by obtaining X-ray diffraction studies. The extent of peak broadening will give you an idea of the presence of these precipitates. The larger the volume fraction or density of these precipitates the more strain it will introduced in the matrix. The larger strain causes more hindrance to the movement of the dislocation. Analytically, if you know the volume fraction, misfit parameter, particle size then you can directly used the equation based on strengthening contribution of the needle-like shearable particles.

Hope it will help you.

Thank you Dr. Murshid,  In undeformed Al-Mg-Si Alloy,  It is well known that beta double prime precipitates contribute maximum strengthening by its coherency with the matrix. In cryorolling of aluminium alloys, the common practice is,  plastic deformation at supersaturated solid solution state followed by low temperature ageing. I would like to know, whether the preexistence of dislocations due to plastic deformation will have any influence of misfit strain and coherency of the precipitates with the matrix. Kindly suggest... 

Hi,

I guess you can modify existing dislocation models based on type G*b over the particle distance with respect to the primary slip system in FCC. The precipitation in this system is primarily taking place  on the cube edges so the projection of the precipitates on the slip system is a straight forward procedure. Since the contrast from beta double prime is quite good it would be easy to measure the density in TEM.

Best wishes

Sten