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 Zn Additions on the Mechanical Properties of High Strength Al–Si–Mg–Cu Alloys
In this study, the effect of Zn additions on the mechanical properties of Al–Si–Mg–Cu alloys was investigated. From the results, it has been found that the formation of Mg–Zn intermetallic compounds is considered to be the main reason for the sharp changes in the mechanical properties of this alloy system. The microstructure showed that Mg–Zn intermetallic compounds were formed between the reinforcement phase like Mg2Si phase and the matrix became more brittle as the amount of Zn addition was increased. Upon these results, we could confirm that the formation of Mg–Zn intermetallic compounds and brittle matrix are the main reasons for the remarkable changes in the mechanical properties of this alloy system.
Finite Difference Modeling on the Temperature Field of Substrate in Friction Surfacing
Friction surfacing is an advanced process of great potential, especially in the field of repair and reclamation of worn and damaged components. As a kind of thermal processing technology, the temperature profile and changes of the substrate in friction surfacing are important factors to get coatings of high quality. In this paper, the temperature field of the substrate during the process is simulated by finite difference method. The results are consistent with experiments, reappearing the temperature change of the substrate during friction surfacing, allowing further study on figuration and quality of coatings.