S. Can Kurnaz

Production of saffil fibre reinforced Zn-Al (ZA 12) based metal matrix composites using infiltration technique and study of their properties

Abstract In this study metal matrix composites of a zinc–aluminium based alloy (ZA-12) and short staple δ-alumina saffil fibres with volume fractions of 0.10, 0.15, 0.20 and 0.30 were produced using a liquid infiltration technique. The densities, hardness, tensile strength and wear properties were examined. The measured densities of the specimens showed that about 90% of the total metal infiltration had taken place at pressures below 1 MPa, and additional pressures up to 3 MPa provided only for the metal infiltration into narrower inter-fibre channels to be completed. The hardness of the composites on both planar and transverse sections increased with the increasing fibre volume fractions, the latter being larger than the former. The tensile strength and the elongation of the composites decreased with increasing fibre volume fractions due to the fibre contact effect. The wear behaviour of the composites was dependent on fibre volume and the applied load. The wear rate of the composites decreased with increasing fibre volume fraction and increased proportionally to the applied load. The wear rate of the unreinforced ZA 12 alloy increased with the load. The coefficient of friction of the composites decreased with increasing applied load and had no definitive trend with the fibre volume fraction. Wear mechanism for the surface of the unreinforced alloy was plastic deformation, whereas for the composites it was the layer deformation on the surface of the composites.

The Effect of Ti–B and Sr on the mechanical behaviour of the Zinc–Aluminum-based ZA-12 alloy produced by gravity casting

Abstract In this study, the effect of Ti–B (0.05–0.7wt.% Ti, 0.01–0.13wt.% B) and Sr additions (0.05–0.7wt.%) on the hardness, ultimate tensile strength (UTS), strain and fatigue properties of the gravity cast Zn–Al-based ZA-12 alloy was investigated. While the Ti–B additions had no significant effect on the hardness of the alloys, the Sr additions lowered the hardness by a small amount. UTS and fatigue resistance of the ZA-12 alloy increased with 0.05wt.% Ti, but the addition of 0.05wt.% Sr to the standard alloy did not change these properties significantly. In excess of 0.05wt.% Ti and Sr, the UTS and fatigue resistance of the alloys decreased and reached a lower value than that of the standard alloy. The failure strain only increased for the ZA-12 alloy containing 0.05wt.% Ti, then decreased with further increase in Ti content. The failure strain values of the alloys decreased with addition of Sr. Metallographic examination indicated that the addition of Ti–B strongly modified the microstructure of the standard ZA-12 alloy, but Sr did not. Ti and Sr have also formed complex-shaped intermetallic compounds, which were identified as Al5Ti2Zn and Zn5Al3Sr by X-ray diffraction and EDS analyses. It can be suggested that these particles cause a decrease in UTS, fatigue resistance, and strain to failure of the ZA-12 alloy.

The effect of Sn (0, 0.5, 1 and 3 wt.%) on the mechanical properties of gravity casting Mg-3Al alloy and a neural network application for prediction

In this study, the influence of Sn (0, 0,5, 1 and 3 wt.%) addition on the yield and ultimate tensile strength (UTS) and elongation values of Mg-3Al alloy was investigated. The alloys were produced under a controlled atmosphere by a gravity-casting process. The results show that yield and ultimate tensile strength of based alloy increased by adding Sn up to 1 wt. %. These ultimate tensile tests and casting process are taking a lot time and cost. So, a neural network (NN) model was developed for prediction these mechanical effects using varied Sn additions. At the end of the testing whether the NN model is suitable for this case, it was seemed that results checked the system accuracy.

Influence of strontium addition on the mechanical properties of gravity cast Mg-3Al-3Sn alloy

In this study, the effect of strontium (0.01, 0.1, 0.5, 1 wt%) addition on the microstructure and mechanical properties of the gravity cast Mg-3Al-3Sn alloy were investigated. X-ray diffractometry revealed that the main phases are α−Mg, β−Mg17Al12 and Mg2Sn in the Mg-3Al-3Sn alloy. With addition The tensile testing results showed that the yield and ultimate tensile strength and elongation of Mg-3Al-3Sn alloy increased by adding Sr up to 0.1 wt.% and then is gradually decreased with the addition of more alloying element.