A martensitic transformation between bcc (α) and hcp (ε) phases can be characterized by four pressures (Table I): a start and end pressure of directα→ε(P_Start^(α→ε) , P_end^(α→ε)) and reverseε→α (P_Start^(α→ε) , P_end^(α→ε)) transformations. Because martensitic stress is present in the anisotropic hcp phase but not in the isotropic bcc phase, we suggest the inequality for the α-ε equilibrium coexistence pressure P0 and the observed hysteresis, rather than an inaccurate simple average[3]