الفهرس 
Imperfections in crystalline solidsOnly 14 pages are availabe for public view
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Abstract
The present work fundamentally covers studying the effect of adding ZnO nanoparticles of thermal, structural and tensile properties of Sn- 5 wt% Sb - 1.5 wt% Ag (SSA515) solder alloy. Four topics are discussed:
1) Studying the effect of ZnO nanoparticles addition on thermal and microstructure characteristics of SSA515 plain solder.
2) Studying the effect of strain rate ε• and testing temperatures (T) on the stress-strain characteristics of SSA515 plain and SSA515 composite solders.
3) Studying indentation creep characteristics of the two solder alloys. The experimental results were performed under different loads.
4) Studying the effect of aging temperature and indentation creep behavior in both plain and composite solder alloys. The indentation creep experiments were carried out under different loads.
In the first topic, Thermal analysis and microstructure evolutions of both the plain and composite solders were examined. Thermal properties of the selected solder alloys have been studied using the differential scanning calorimetry (DSC) and the microstructure was examined by scanning electron microscopy (SEM) and energy dispersive X-ray spectrometer (EDS). Phase identification of the alloy samples was accomplished by X- ray diffractometry (XRD). The results showed that the observed endothermic peaks of the SSA515 plain solder and SSA515 composite solder were found shifted from 239.71 to 239.63 oC. For each solder, only one peak is observed and the melting temperature of the SSA515 composite solder was found slightly lower than that of the conventional SSA515 solder by about 0.8oC. Microstructural analysis revealed that Ag3Sn and SnSb IMC particles and the β-Sn phase were exposed in both SSA515 plain and SSA515composite solders. Addition of 0.3 wt% ZnO nanoparticles yielded uniform dispersion of these IMCs within the Sn-rich mixture producing a fine connection such as microstructure with the β-Sn.
In the second topic, stress-strain tests for solders under investigation were performed under different strain rates ε• ranged from 4.4 x 10-3 to 0.13x 10-3 s-1 at different testing temperatures in the range from 298 to 373 K. The results showed that increasing strain rates or/and decreasing the testing temperatures and the existence of the nano-sized ZnO particles resulted in increasing the work hardening parameter (WHP) ultimate tensile stress UTS, offset yield stress 0.2y and stress exponent (n). The level of the above(WHP) were always higher for composite solder than plain one.The activation energy Q for plain and composite solders exhibits a durable dependence on the addition of ZnO and variation of strain rate. For composite solder, it decreases from ~0.78 to 0.54 eV, whereas for the plain solder it slashed from ~0.74 to 0.4 eV with average activation energies of ~0.57eV for the plain and ~0.66 eV for the SSA composite LFS alloys, respectively.
In the third topic, microhardness tests were conducting using Vicker hardness tester at room temperature using loads of 0.098,0.245,0.490,and0.980 N for dwell times ranging from 5 to 300s. The hardness of ZnO-contained solder at different loads was found of higher values than those of plain solder.
In the fourth topic, the creep behavior of plain and composite solders was studied using indentation measurements at different loads for samples thermally aged for 24h. at 125oC and 175oC and compared with the as-cast samples. The changes in microhardness with dwell time in plain and composite solder alloys as cast, aged at 125 oC and 175 oC showed that Hv increased with increasing aging temperature which may be explained by the redistribution process of IMCs according to the surface energy property.