In this study, casting A356 alloy was pre-alloyed with Ni, and the modification process with Sr was applied by the casting method. The role of Ni on the microstructural and mechanical properties of the produced A356-Ni alloys was investigated. The produced alloys were naturally aged at room temperature for 24 h and artificially aged at 170 • C for 10 h. Optical microscopy (OM), scanning electron microscopy (SEM), and X-ray diffractometer were used in microstructure studies of the A356-Ni alloys. Tensile tests and hardness measurements were carried out to determine mechanical properties. Statistical analysis of Weibull distribution on the tensile test results revealed that the characteristic ultimate tensile strength increased due to increasing the amount of alloying elements, while the characteristic percentage elongation is decreased. This was because Al-Si-Fe intermetallic decomposition and Al-Si-Fe-Ni intermetallics were formed, primarily, 0.5 and 1.0 % Ni addition. It was also determined that the Al-Si-Fe-Ni intermetallics with a morphology non-sharp corners formed more homogeneous in the microstructure. But in the A356 alloys with the addition of 1.5 % Ni, Al-Si-Fe-Ni intermetallics are formed in coarser morphology. In A356 alloys, aluminium dendrites, Al-Si eutectic between dendrites, Mg2Si precipitates are formed in the structure by ageing. Depending on the amount of Ni added to the A356 alloy, the tensile strength of the alloys containing 0.5 and 1.0 % Ni is increased.

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This study investigates microstructures and mechanical properties of the alloys obtained by adding Cu (0.7 % and 0.9 %) and Al (0.7 % and 0.9 %) to lead-free Sn-9Zn eutectic soldering alloy produced by investment casting method. The results show that Cu5Zn8 phase has formed in the structure of Cu added alloys and the Al2O3 phase has formed due to addition of Al. It was found that small and round-shaped Al2O3 phase increased the tensile strength of the new alloy compared to the eutectic alloy. In addition, it was observed that the microhardness of Cu added alloys was lower than that of Sn-9Zn eutectic alloy, but the microhardness of alloys containing Al was higher compared to the other eutectic Sn-9Zn alloy.

In this study, the effect of milling time on wear behavior of the AISI 304 stainless steel produced by the mechanical alloying method was investigated. In the study element powders were prepared and mechanically milled at five different milling times (30, 60, 90, 120, and 150 min) in a mechanical alloying device. The milled powders were pre-shaped and sintered at 1300 • C for 1 h and cooled to room temperature in the furnace. Produced samples microstructure and XRD examination were carried out. Wear tests were performed using a pin-on-disc type wear testing device. In this study, the hardness values were found to have increased by increasing milling time. The maximum hardness values were measured for the 150 min milled samples. The lowest weight losses were measured with 150 min milled samples. The wear test results were compatible with hardness results.

In this study, the microstructure and mechanical properties were investigated of different amount Cr (0.1%, 0.5%, 0.9%) added Sn-9Zn eutectic alloys and Weibull statistical analyses were evaluated using ultimate tensile strength. Pure elements (Sn, Zn, Cr) were used for production of alloys and pre-alloying was done and waited in the electrical resistance furnace at 450 • C for 1 h to homogenized and poured as ingot in plaster moulds. Then pre-alloyed Sn-9Zn-xCr ingots were melted and poured at 300 • C in ceramic moulds prepared investment casting method. As a result of the study, the highest hardness and ultimate tensile strength values were measured in the Sn-9Zn alloy with 0.1% Cr. It was determined that while ultimate tensile strength was decreased, percentage of elongation was increased by increase of Cr amount. According to the Weibull statistical analyses results, the highest Weibull module was calculated by Sn-9Zn-0.1Cr alloy ultimate tensile strength values.