= Solution
\b[The profile estimate and equilibrium lever-rule estimate need not agree exactly.] The height trace contains only four major ridges, making it a small sample of the microstructure. Pixel size, ridge-threshold choice, tip geometry, contamination, polishing damage and unequal etching change apparent widths. A finite-radius AFM tip can broaden the narrow raised <cementite> regions, biasing their inferred fraction upward.
The equilibrium calculation assumes eutectoid <pearlite> with the chosen carbon composition and tie-line values. Off-eutectoid <steel> can include proeutectoid <ferrite> or <cementite> outside the <pearlite>; alloying, carbon segregation and non-equilibrium cooling alter the simple Fe–C estimate. Carbon solubility also varies with <temperature>. The mass-to-volume conversion requires phase densities.
The observed difference between roughly $17\%$ ridge fraction and $11\%$ equilibrium phase volume is therefore a reason to examine sampling and the etched-surface measurement, not to <force> the image widths to match the <lever rule>. Multiple colonies, repeated calibrated traces and a phase-sensitive measurement would improve the comparison.
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