Studying Effect of Adding Nickel to Al-Cu Alloy Before and After Heat Treatment

Abstract

In this research, the effect of adding pure nickel element in different amountsAl-4%Cu-1.5%Mg) has been studied it (to molten alloy (1-2-3-5%wt)making the heat treatment (T6) which includes solution treatment followed byartificial aging at 220 ºC at different times within the range (5 min.-5 hr.)). Alsothe effect of nickel element on the microstructure, the grain size and the phasestype which are constructed in the produced alloys by alloying before and afterheat treatment by using optical microscope and X-Ray diffraction test device havebeen studied then the hardness and tensile test were implemented and then theresult showed: the alloy with the highest adding rate (5% wt) shows a better response than the other alloys for hardening in longer time period where it havebeen reached to highest hardness (125 H.V) in time period (4hr) at (220 ºC).While the empty alloy of nickel reached to highest hardness equals to (112 H.V)in a time period less than (2hr). The constructed phases in alloys have beenspecified after adding Ni element, where it indicated to the existence of the phase(Al7Cu4Ni) which is responsible for the slowliness which occurs in the alloy’sresponse to precipitation hardening procedure which leads to delay (longer timeperiode) to obtain a higher hardness. It also found that adding of nickel causes anincrease and an improvement in the properties of the tensile strength, yieldstrength and elongation, which indicates that the presence of the nickel takes twoways part of it dissolve with Aluminum and copper to produce the phase(Al7Cu4Ni) which causes the slowing in the construction of the hardening phase(Al2CuMg), the other part causes refining grains size at the highest temperaturedegrees causing an increase in the strength and the hardness in a rate which ishigher for the alloy’s that contain nickel in a comparison with the empty alloy ofnickel.