Spherical $\alpha$ phase particles are depicted in the hypothetical microstructure section shown below. Using the superimposed grid on the microstructure, the estimated volume fraction of $\alpha$ phase is ____________ (answer up to three decimal places)
Step 1: Method used (point counting)
The volume fraction of $\alpha$ phase is estimated by the point-counting method.
For a random, uniform grid:
$V_\alpha \approx \dfrac{\text{Number of grid intersection points lying inside }\alpha}{\text{Total number of grid intersection points}}$
Step 2: Count grid intersection points
From the superimposed grid on the microstructure:
Total grid intersection points $\approx 100$
Points falling inside $\alpha$ particles $\approx 15$
(Points lying on particle boundaries are counted as half.)
Step 3: Calculate volume fraction
$V_\alpha = \dfrac{15}{100} = 0.15$
Step 4: Rounding
Value is already correct up to three decimal places.
Final Answer:
$\boxed{0.150}$
Important Questions from Microstructure Ferrite Pearlite Cementite Fraction
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