Effect Of Macro Additions Of Zinc And Nickel On The Mechanical And Microstructural Properties Of A Modified 7xxx Aluminium Alloy
There has been large interest in combining the light weight of aluminium with varied excellent mechanical properties that a metal should poses for various industrial applications. This interest has led to vigorous researches in improving the mechanical properties of aluminium.This paper therefore investigatesthe effect of macro additions of zinc and nickel on the mechanical and microstructural properties of a modified 7xxx aluminium alloy. In this investigation, a corresponding relationship has been established between the microstructure and the properties of aluminium. Using the process of stir casting, Zinc was added to Al2.5Mg7Ni and Al2.5Mg2Ni to cast samples which were later homogenized at 550 o C and tempered (T6). Mechanical properties including, tensile strength, tensile elongation, hardness and fracture strength were investigated. Result shows that cast samples containing 15wt%Zn and 2wt%wtNi exhibited superior tensile strength (128.5MPa) and (0.0419) which is attributed to the presence and even distribution of Mg2Si and NiAl3 intermetallic, in the microstructure of the as-cast material. Solution treatment at 550 o C led to a good combination of tensile strength and elongation (111.72MPa and 10%). Increase in Nickel content led to a stabilization of the material structure but did not impart strength and ductility. T6 tempering of solution treated samples did not give any increase in the mechanical properties. Microstructure of cast structure shows the presence of three intermetallic including NiAl3, AlFeSi and Mg2Si in the α-aluminium matrix.
Effect of Ni–Mg on the microstructure and properties of Al–(4–5)Fe–1V–1Si alloys
The paper deals with solidification behaviour, microstructure and mechanical properties of Al–(4–5)Fe–1V–1Si alloys. The alloys are prepared in a resistance-heating furnace and cast in a permanent mould at a cooling rate of 30 K/s. The solidification proceeds through several invariant reactions irrespective of treatment. The melt is treated with Ni–Mg master alloy in order to change the morphology, size and distribution of the primary as well as interdendritic phases. The treated alloys show an increase in first invariant reaction temperature and decrease in final invariant reaction temperature when compared with untreated alloy. With increasing amount of Ni–Mg master alloy addition the temperature of the first invariant reaction further increases and the final invariant reaction temperature decreases, probably due to action of grain refinement and phase modification. In comparison to untreatable alloy, appreciable improvement in mechanical properties occurs on modification by Ni–Mg treatment. Hot rolling further improves the mechanical properties of the alloy.
Secoiridoids from Olea europaea
Abstract Three new secoiridoids have been isolated from the leaves of Olea europaea along with the previously reported. The compounds were identified by spectral means.