الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 218 |  |  |
| | | from | 218 | | |
Abstract
The Sn-Zn solder alloys are considered nowadays a good replacement for the Pb-based solder alloys due to it’s thermal stability and the environmental concerns, the trials aimed making enhancement and improvement in their properties, these trials are going to be continued nowadays and in the near future until finding an excellent candidates for the lead-based solder alloys, and one of these trials is the current study which aimed:
I) Investigating the influence of third element addition such as minor amount of nanometric material represented in the form of ZrO2 on the thermal, structural, and mechanical properties of the eutectic Sn-9Wt. %Zn (SZ) lead-free solder alloy.
II) Studying the effect of Ni additions with different ratios, but in a small concentrations range as follows:
0.1Wt.%,0.2Wt.%,0.3Wt.% on the thermal, structural, and mechanical properties of the eutectic Sn-9ZnWt. % (SZ) lead-free solder alloy.
III) Exploring the influence of different operating temperatures on the hardenability of the eutectic Sn-9ZnWt. % (SZ) lead-free solder alloy till obtaining the goal of the research.
IV) Inspecting of the influence of the strain rate and the different additions of Ni element on the thermal, structural, and mechanical properties of the plain solder represented in the form of Sn-9ZnWt. % (SZ) lead-free solder alloy.
V) Investigating the effect of nanometric additions of ZrO2 and Ni element with different ratios on the mechanical properties in order to investigate the hardness of Sn-9Wt.%Zn solder alloy using Vicker hardness test.
In order to verify the previous mentioned goals, the next
mentioned points are applied:
1.preparion of the five solder alloys which are as follows:
The first solder alloy is the plain solder alloy eutectic Sn-9Wt.% Zn, the other four solder alloys have the same structure of the plain solder alloy with the addition of nanometric materials with concentrations equal to: 0.5Wt.% of ZrO2 which symbolized as follows:
(SZ-ZrO2), while the third, fourth, and fifth solder alloys are prepared by the addition of Ni with different ratios as follows:0.1Wt.%,0.2wt.%, and 0.3wt.% and symbolized as follows:(SZN901), (SZN902), and (SZN903).
2.By using the X-ray diffraction technique (XRD), and by utilizing the differential scanning calorimetry technique (DSC) in order to investigate the internal structure, the existing phases, and also the thermal characteristics of the testing solder alloys.
3.In the current study, the stress-strain, which is a tensile test technique, is performed to inspect the effect of the strain rate and working temperatures on the mechanical properties of the investigated alloys.
4.Finally, Vickers hardness test is performed to measure the hardness of the current solder alloys and to observe a material’s ability to resist plastic deformation from a standard source, and the influence of the previously mentioned additions on the plain Sn-9ZnWt. % solder alloy.
The obtained results are represented as follows:
1.The results showed the presence of the fine intermetallic compounds Ni5Zn21 and Sn3Ni4Zn3 phases which are confirmed by using the X-ray diffraction technique.
2.The addition of ZrO2 in the nanometric form and also the different ratios of Ni cause:
a. Increasing and enhancing in the tensile parameters which are yield stress σy and ultimate tensile stress σUTS.
b. An obvious decrease in the previously mentioned parameters yield stress σy and ultimate tensile stress σUTS with increasing the applied working temperatures.
c. The results obtained demonstrate that small Ni addition causes a major grain refinement of β-Sn, due to the formation of the fine intermetallic compounds Ni5Zn21 and Sn3Ni4Zn3 phases and refines the formation of α- Zn lamellar phase which are shown in the optical microscope images(OM), and confirmed using the scanning electron microscope with increasing the ratios of Ni additions which coincide with deduced values from the stress-strain test therefore, from the previously mentioned points a, b we deduced that the current additions have a great effect in improving the mechanical properties of the plain solder Sn-9Wt.%Zn and increasing its hardness.
d. Considerable enhancement in the hardness properties of the tested solder alloys with the previously mentioned elements additions and its resistance to plastic deformation from a standard source are also confirmed using the Vickers hardness tests which represents one of the goals of the current study.
e. The results confirmed a noticeable improvement in the thermal properties and melting temperatures of the tested solder alloys SZ, SZN901, SZN902, SZN903, SZ-ZrO2, the melting temperature of the recently discovered solder alloys was lower than that the eutectic Sn-9ZnWt. % (∆Tm" ~ "28 ºC) as a result of the preparation technique and incorporation of Ni and ZrO2 nanoparticles.
f. The enhanced strength of the SZ-ZrO2 alloy defended the results of the σUTS and increased the stress exponent n, by" ~ "20% all solders had an activation energy Q that measured between ∼35.62 kJ/mol to ∼58.12 kJ/mol which comparable to the pipe-diffusion mechanism.