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    Öğe
    Influences of Growth Velocity and Fe Content on Microstructure, Microhardness and Tensile Properties of Directionally Solidified Al-1.9Mn-xFe Ternary Alloys
    (Univ Fed Sao Carlos, Dept Engenharia Materials, 2017) Cadirli, Emin; Aker, Aynur; Kaygisiz, Yusuf; Sahin, Mevlt
    In this study, influences of growth velocity and composition (Fe content) on the microstructure (rod spacing) and mechanical properties (microhardness, ultimate tensile strength and fracture surface) of Al-Mn-Fe ternary alloys have been investigated. Al-1.9 Mn-xFe (x= 0.5, 1.5 and 5 wt. %) were prepared using metals of 99.99% high purity in the vacuum atmosphere. At a constant temperature gradient (6.7 K/mm), these alloys were directionally solidified upwards under various growth velocities (8.3-978 mu m/s) using a Bridgman-type directional solidification furnace. The results show that two kinds of Al-rich alpha-Al phase and Fe-rich intermetallic (Al 6 FeMn) phase may be present in the final microstructures of the alloys when the Fe content increases from 0.5 wt.% to 5 wt.%. Al 6 FeMn intermetallic rod spacing, microhardness and ultimate tensile strength were measured and expressed as functions of growth velocity and Fe content by using a linear regression analysis method. According to experimental results, the microhardness and ultimate tensile strength of the solidified samples increase with increase in the growth velocity and Fe content and decrease in rod spacing. The elongations of the alloys decrease gradually with increasing growth velocity and Fe content.
  • [ X ]
    Öğe
    Microstructural, Mechanical, Electrical, and Thermal Properties of the Bi-Sn-Ag Ternary Eutectic Alloy
    (Wuhan Univ Technology, 2017) Kaya, Hasan; Engin, Sevda; Aker, Aynur; Buyuk, Ugur; Cadirli, Emin
    The development of lead-free solders has emerged as one of the key issues in the electronics packaging industries. Bi-Sn-Ag eutectic alloy has been considered as one of the lead-free solder materials that can replace the toxic Pb-Sn eutectic solder without increasing soldering temperature. We investigated the effects of temperature gradient and growth rate on the mechanical, electrical and thermal properties of the Bi-Sn-Ag ternary eutectic alloy. Bi-47 wt% Sn-0.68 wt% Ag alloy was directionally solidified upward with different temperature gradients ( G=2.33-5.66 K/mm) at a constant growth rate ( V=13.25 mu m/s) and with different growth rates ( V=6.55-132.83 mu m/s) at a constant temperature gradient ( G=2.33 K/mm) in the growth apparatus. The microstructures (lambda), microhardness ( HV), tensile stress ( sigma), electrical resistivity (rho), and thermal properties (Delta H, C-p, T-m) were measured on directionally solidified samples. The dependency of the lambda, HV, sigma, and rho on G and V was investigated. According to the experimental results, lambda values decrease with increasing G and V, but HV, lambda, and rho values increase with increasing G and V. Variations of electrical resistivity (rho) for cast samples with the temperature in the range of 300-400 K were also measured by using a standard dc four-point probe technique. The enthalpy of fusion (Delta H) and specific heat ( C-p) for the same alloy was also determined by means of differential scanning calorimeter ( DSC) from heating trace during the transformation from eutectic liquid to eutectic solid.