الفهرس 
Chapter I IntroductionOnly 14 pages are availabe for public view
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Abstract
The present work mainly focuses on studying the effect of adding Ni element and graphene oxide nano sheets (GONSs) on thermal, microstructure, and mechanical properties of Sn- 5 wt.% Sb- 0.7 wt.% Cu alloy. Three topics are discussed:
Studying the effect of Ni element and graphene oxide nano sheets (GONSs) on thermal and microstructure characteristics of SSC-507 plain solder.
Studying creep characteristics of the three solder alloys. The experimental results were investigated under different levels of stress and temperature.
Studying the effect of strain rate, ε ̇, and testing temperatures, T, on the stress-strain characteristics of SSC-507, SSC-0.1Ni, and SSC-0.1Ni-0.1GONSs wire samples.
In the first topic, thermal analysis and microstructure evolutions of the Sn- 5 wt.% Sb- 0.7 wt.% Cu (SSC-507), SSC- 0.1 wt.% Ni solders, and the composite solder SSC- 0.1 wt.% Ni- 0.1 wt.% GONSs were discussed. Thermal properties of the three solder alloys have been studied by using the differential scanning calorimetry (DSC) and the microstructure was examined by scanning electron microscopy (SEM), electron probe micro analyzer (EPMA), and energy dispersive X-ray spectrometer (EDX). Phase identification of the alloy samples was carried out by X- ray diffractometry (XRD). The results showed that the observed endothermic peaks of the SSC-507, SSC-Ni, and composite SSC-Ni-GONSs were shifted from 237.16 to 238.18 to 237.92 ℃ respectively. For each solder, only one peak is observed and additions of Ni and GONSs have a slight effect on the melting property of SSC-507 solder during the heating process. The microstructure of SSC-507 solder alloy was composed of light gray islands of non-equiaxed, non-uniform β-Sn grains and large dark network-like eutectic regions contain mixture of lamellar phases of Sn matrix with large number of small sized SbSn IMC and without any massive Cu6Sn5 IMC. The addition of Ni into the lead-free SSC-507 solder alloy led to formation of new phases like (Cu,Ni)6Sn5 on the expense SbSn phase. Whenever incorporation of GONSs to SSC-Ni solder alloy led to a noticeable reduction in the average grain size of β-Sn rich phase.
In the second topic, tensile creep tests of the SSC-507, SSC-Ni, and composite SSC-Ni-GONSs solders were carried out at temperatures ranging from 298 to 398 K under effect of different applied stresses ranged for 7.6 to 14 MPa. It can be noticed that isothermal creep curves of both solders showed a monotonic shift towards higher strains and lower fracture times with increasing testing temperature and/or applied stress. At constant applied stress and testing temperature, SSC-507 alloy had the lowest creep resistance and highest creep strain. Adding of 0.1 wt.% Ni and 0.1 wt.% GONSs can clearly increase the creep resistance and decrease the creep strain successively. Adding 0.1 wt.% GONSs can clearly increase the creep-rupture life nearly 2.5 times greater than that of plain solder alloy (SSC-507) and about 1.5 times better than SSC-Ni alloy. The obtained values of activation energies are in good agreement with those given in the case of dislocation pipe diffusion.
In the third topic, stress-strain tests for SSC-507, SSC-Ni, and composite SSC-Ni-GONSs solders were performed under the effect of different strain rates, ε ̇, from 8.79x10-5 up to 1.96x10-3 s-1 at different testing temperatures, T, in the range of 298 to 398 K. The results showed that increasing strain rates, or/and decreasing the testing temperatures, and the existence of Ni element and GONSs resulted in increasing the work hardening parameter (WHP) [yield stress (y), Young’s modulus (Y), ultimate tensile stress (UTS), work hardening coefficient (χ_P), and stress exponent (n)]. The average activation energies of SSC-507, SSC-0.1Ni, and SSC-0.1Ni-0.1GONSs are 41.64, 42.22, and 46.5 kJ/mol (" ~ "0.5 of QSn) respectively. These values of activation energies are less than those for lattice self-diffusion of β-Sn (QLSD≈100 kJ/mol).