Structure and crystal growth in melt-spun Fe81Ga19 alloys

Adopting the single roller melt-spinning technique, the Fe81Ga19 ribbons with the thickness of 80 and 25 μm were fabricated at a linear velocity of 5 and 30 m/s, respectively. The microstructural study shows that the ribbons exhibit an initial chill zone on the contact side, leading to columnar growth with an equiaxed zone adjacent to the free side. The formation mechanism of the microstructure is also discussed. The temperature distribution and the cooling rate of the ribbon are calculated in terms of a one-dimensional heat conduction model. When the liquid solidifies, the cooling rate on the free side is estimated to be 3.017x106 and 3.089x107 deg. C/s for the Fe81Ga19 ribbons with the thickness of 80 and 25 μm, respectively