Effects of melting cycles on the microstructural morphology of a melt--spun Al90Pb10 alloy
热循环对快速凝固Al90Pb10合金结构形态的影响

An AI90Pb10 alloy has been melt-spun into ribbons. As Pb and Al are immiscible at room temperature, the melt-spun ribbons were composed of dispersive nanometer-sized Pb particles embedded in Al matrix. By means of differential scanning calorimetry (DSC) to cycle heating and cooling, the Pb nanoparticles in the melt-spun ribbons undergo three melting-solidifying cycles. Microstructures of both the as-spun and the treated samples were studied by transmission electron microscopy (TEM). It was found that the average size of Pb nanoparticles increased obviously and most of the Pb particles with a size less than 10 nm disappeared after the heat treatment cycles. Meanwhile, Orowan dislocation rings were observed among the grown Pb particles after cycles. That is, Ostwald ripening of Pb nanoparticles occurred in the immiscible AI90Pb10 alloy during the heat treatment cycles. The evolution mechanism of structure and morphology was also discussed.