STUDY OF SUPERPLASTICITY IN THE Pb-Sn-Zn TERNARY ALLOYS

AbstractThe research concerned with the study of superplasticity in (Pb-65.5Sn-3.4Zn) and (Pb-65Sn-1Zn) ternary alloys. These alloys chosen in the present study because of they are a candidate materials to be useful for various microelectronic connection in compuIn the first section, the transient creep is studied at different applied stresses ranging from 3.123 to 6.83 MPa and at different test temperatures near the transformation temperatures in the temperature range from 353 to 413 K. The results of creep charThe parameter ? was related to steady state creep rate (?st) through the equation {?=?0(?st)*}. This equation was found to be valid with the exponent ? ranging from 0.76 to 0.96 and from 0.63 to 0.93 for Pb-65.5Sn-3.4Zn, and Pb-65Sn-1.0Zn alloys, respectiThe activation enthalpies of the transient creep below and above the transformation temperature have been found to be 20.53 and 55 kJmol-1 for Pb-65.5Sn-3.4Zn, and 22.66 and 58.23 kJmol-1 for Pb-65Sn-1Zn alloy, in low and high temperature regions, respectThe stress dependence of n and ? shows a threshold value, which decreases as Zn content increase. The enhanced values of n and ? for the eutectic alloy is started at ? ?4.75 MPa while for the ternary alloy at ? ?5.2 MPa depending on the Zn content in bothThe steady state creep of the alloys were investigated in the same temperature range and stresses previously mentioned. The results of creep characteristics show (one transition point at 383 K) two deformation regions (below and above 383 K). The strain rThe steady state strain rate ?st at any particular temperature was found to increase monotonically by increasing the applied stresses and the transformation temperature. The steady state strain rate ?st was found to exhibit values ranging from 4.7x10-3 toMoreover, the change in electrical resistivity of Pb-65.5Sn-3.4Zn eutectic and Pb-65Sn-1.0Zn ternary alloys were measured at various ageing temperatures for various ageing times. Both alloys showed enhancement in the reaction rate in comparison to those oThe values of activation energies of formation and dissolution of precipitates are of 9.3 kJmol-1 and 12.1 kJmol-1 for Pb-65.5Sn-3.4Zn ternary eutectic alloys, and 9.9 kJmol-1 and 13.2 kJmol-1 for Pb-65 Sn-1.0Zn ternary alloys, in low and high temperatureThe variation in the microstructure of both alloys during creep processes as a function of working temperatures have been investigated using, Optical Microscope (OM), Scanning Electron Microscope (SEM), and Transmission Electron Microscope (TEM). Our resuThe hardness also, is studied for the two alloys. They have the same behavior. The addition of Zn content leads to reduce the hardness i.e. show superior superplastic behavior.Differential Thermal Analysis (DTA) for Pb-65.5Sn-3.4Zn ternary eutectic and Pb-65Sn-1.0Zn ternary alloys were measured. It is clear that, as Zn-content increases up to 3.4% Tm decreases from 455 K for Pb-65Sn-1.0Zn ternary alloys to 477.9 to Pb-65.5Sn-3.