The Study of Unidirectional Transformation of Copper-Aluminium Eutectoid Alloy Controlled by the Heat Flow

Cu-Al eutectoid alloy has been transformed unidirectionally to produce aligned pearlitic structure in an electric resistance furnace under the temperature gradient of ∼150°C/cm and with the translation velocity from 0.28 to 5 mm/hr.At lower translation velocities, well-aligned pearlite paralell to the heat flow direction was produced. However, at higher velocities, a “zigzag” or “herringbone” structure was produced. The relationship between translation velocity (R) and interlamellar spacing (λ) was determined. At low velocities a growth law of Rλ3.7=const. existed. As the growth velocity increased, the exponent in the growth law continuously changed from 3.7 to 1.2. The change in R-λ relationship over a wide velocity range was consistent with the theoretical analysis by Carpay.