Classification 上浒充通大兽 SHANGHAI JIAO TONG UNIVERSITY Both precipitation and eutectoid transformations: ■ Composition change? ■ Involve the formation of phases with a different composition to the matrix>Long-rang diffusion is required Ordering,massive and polymorphic transformations: ■ Composition change? No composition change no long-range diffusion AO TONG K.Chen 18K. Chen Classification 18 Ordering, massive and polymorphic transformations:  Composition change?  No composition change  no long-range diffusion Both precipitation and eutectoid transformations:  Composition change?  Involve the formation of phases with a different composition to the matrix  Long-rang diffusion is required