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Grain refinement of Al–Si alloys is one of the effective methods for improving the elongation (El) and ultimate tensile strength (UTS). The influences of alone adding Ni (0.5, 1.0, 1.5, and 2.0%) and complex adding Ni (0.5, 1.0, 1.5, and 2.0%) plus 0.4%Y on the evolution of α-Al, eutectic Si, as well as mechanical performance of Al–7Si alloy, were investigated. All specimens were characterized by electron probe microanalysis, transmission electron microscopy, optical microscope, and scanning electron microscope. The results indicated that the secondary dendrite arm spacing (SDAS) of primary α-Al was markedly decreased with increasing Ni content in Al–7Si alloy. When the Ni addition concentration increased to 1.5%, the developed dendritic α-Al were effectively refined into fine equiaxed dendrites. Rare earth Y (0.4%) plus Ni were together added to Al–7Si alloys. The results showed that complex addition of Ni plus Y had a more outstanding refinement effect of α-Al and eutectic Si than that of Ni alone addition in Al–7Si alloy. The coarse and needlelike eutectic Si was modified into fine fibrous shape, and the SDAS of α-Al was significantly reduced when 1.5%Ni plus 0.4%Y was simultaneously added to Al–7Si alloy. Meanwhile, the mechanical performance test illustrated that the El and UTS were improved to 10.8% and 217.8 MPa, respectively.

The crystallization behavior of poly(ɛ-caprolactone) (PCL) in the miscible blends of PCL/poly(vinyl chloride), PCL/poly(hydroxy ether of bisphenol A) and PCL/poly(bisphenol A carbonate) has been investigated by differential scanning calorimetry and polarized light microscopy. Through comparison of the PCL crystallization rate and calculation of the interaction energy density B between the miscible components in these blends, it was found that the effect of the noncrystallizable component on the crystallizability of PCL is not consistent with the strength of the specific interaction in the blends detected by FTIR but coincides with the interaction energy density B. The variation of PCL crystallizability reflects an effect of the “apparent total intermolecular interaction” in the blends. The influences of glass transition temperature, self-associated interaction of the noncrystallizable component and geometrical factors on the PCL crystallization rate and the intermolecular interaction in the blends are also discussed.