The Influence of Nickel and Tin Additives on the Microstructural and Mechanical Properties of Al-Zn-Mg-Cu Alloys

Abstract

The effects of nickel and nickel combined tin additions on mechanical properties and microstructural evolutions of aluminum-zinc-magnesium-copper alloys were investigated. Aluminum alloys containing Ni and Sn additives were homogenized at different temperatures conditions and then aged at 120°C for 24 h (T6) and retrogressed at 180°C for 30 min and then reaged at 120°C for 24 h (RRA). Comparison of the ultimate tensile strength (UTS) of as-quenched Al-Zn-Mg-Cu-Ni and Al-Zn-Mg-Cu-Ni-Sn alloys with that of similar alloys which underwent aging treatment at T6 temper showed that gains in tensile strengths by 385 MPa and 370 MPa were attained, respectively. These improvements are attributed to the precipitation hardening effects of the alloying element within the base alloy and the formation of nickel/tin-rich dispersoid compounds. These intermetallic compounds retard the grain growth, lead to grain refinement, and result in further strengthening effects. The outcomes of the retrogression and reaging processes which were carried on aluminum alloys indicate that the mechanical strength and Vickers hardness have been enhanced much better than under the aging at T6 temper.

Effect of Si Addition on Microstructure and Tribological Properties of Al-0.1Mg-0.35Ni-(4, 6, 8, 10) wt %Si Alloy

“…that the YS increase linearly with the increasing Si content. The increasing YS with the increasing Si content in the aged condition are also due to the presence of intermediate phase Al 3 Ni. Figure 18 shows the %elongation vs. wt % Si plot for the Al-0.1Mg-0.35Ni- (4,6,8,10) wt %Si alloy combination in the aged condition.…”

“…Wear rate results Figure 19 shows the wear rate vs. wt % Si plot for Al-0.1Mg-0.35Ni- (4,6,8,10) wt %Si alloys in the aged condition. The wear rate was found to decrease with the increasing Si content and this behaviour was attributed to the formation of an intermediate phase Al 3 Ni. Figure 20 shows the wear rate vs hardness plot for the Al-0.1Mg-0.35Ni- (4,6,8,10) wt %Si alloys in the aged condition.…”

“…The effect of Ni addition was investigated by Petrick [2], and observed an increase in the hardness. An increase in the hardness and tensile properties for the Ni added alloy [3]. The effect of Ni addition to the Al-Si alloy was studied by Li et al [4] and found the formation of intermediate compound containing Ni.…”

Effects of Ni on the microstructure, hot tear and mechanical properties of Al–Zn–Mg–Cu alloys under as-cast condition

“…In the Ni-containing alloys, Al3Ni phase is formed and acted as strengthening phase due to its high values of Young's modulus (116e152 GPa), hardness (HV0.01 ¼ 5130 MPa) and tensile strength (2160 MPa) [35,36], while the rigid Al3Ni compound is substantially inert in the alloy and acts as hard pinning points restraining dislocation motion which can affect the strength and elongation of Al alloys. Meanwhile, according to the discussion above, the amount of eutectic melt would increase, thus the initial shrinkage porosity can be refilled and healed.…”

“…Recently, Ni was found as a potential element capable of achieving these goals. The addition of Ni in Al alloys can increase the strength at room or elevated temperatures [30e36], which have been widely confirmed in Al-Si [30e33], AleMgeSieMn [34], Al-Si-Cu-Mg [35] and AleZneMgeCu [36] alloys. Meanwhile, Belov et al [37e39] analyzed the equilibrium phase diagram of AleZneMg-(Cu)eNi alloys using Thermal-Calo software, and found that Ni only exists in the form of Al þ Al3Ni eutectics.…”