The linear or mean intercept method is one way to estimate the average grain diameter, d. If you have several cross-sections of your sample so you can determine whether the grains are equi-axed (approximately the same length in all directions), rod or columnar shaped, or platy (like a dinner plate), you can increase the accuracy of your estimate by including a shape factor in your calculation. (i) Use the mean intercept on the schematic microstructure for a hypothetical single phase metal below, to estimate the average grain size. Don't worry about including a shape factor.
Note: Mean intercept length, I = p where L:- measured length of the line(s) on the micrograph, P- number of times the line(s) intersect a grain boundary and M = the magnification of the micrograph; you may need to determine this from the scale bar.
(ii) If you use more than one line and you vary the orientation of your lines will you get a better estimate of the average grain size? Explain your answer in 1-3 bullets.