Stabilization Effect of Zr and Ti Additions on the Ageing Characteristics of Al‐1 wt% Si Alloy Through a Creep Study

Abstract

-0.1 wt% Zr-0.1 wt% Ti alloys were used to trace the effect of Zr and Ti additions on the behaviour of the steady state creep. After solid solution treatment specimens of both alloys were aged at 623, 673, 723 and 773 K and creep tests were performed at room temperature by applying stresses of 60.0, 62.4, 64.7 and 67.1 MPa. The results showed a sound stabilization effect of Zr and Ti on the ageing characterstics of binary Al-1 wt% Si alloy. Values of the applied stress sensitivity parameter, m, obtained were in the range of (20-34) for Al-Si alloy and (14-19) for Al-Si-Zr-Ti alloy. Time to rupture was found to be strongly increased by Zr and Ti additions. The activation energies of the precipitation process involved were found to be 81.9 kJ/mole and 33.7 kJ/mole of the Al-Si and Al-Si-Zr-Ti alloys respectively.

Effect of irradiation and pre-ageing temperature on the mechanical properties of Al–Si alloy

“…In Al-Si alloys, the solubility of Si in Al is negligible (21,22) below 523 K. Therefore, Si exists as a separate phase and vacancy-Si pair migration is therefore favourable (6). Above 523 K, Si precipitates become non-coherent (23) and this leads to a reduction in the microhardness of Al-Si alloys above 573 K. Silicon precipitation in Al-Si alloys quenched at critical temperature was enhanced (5) by pre-ageing near 0 • C. Once the specimen is subjected to this pre-ageing, the number of these precipitates does not change upon heating up to 573 K for 10 min.…”

Development and Characterization of Cast Modified SI-CU-MG Alloys for Heat Resistant Power Train Applications

“…Westengen et al [97] studied the effect of minor additions of transition elements on the recrystallization of commercial aluminum alloys, and reported that Zr works as inhibitor of recrystallization. The effect of Zr and Ti in wrought aluminum alloys was also investigated by other researchers [25,98] and they found that the presence of Si, Zr and Ti formed stable phases with L1 2 , D0 22 and D0 23 type structures which are stable at elevated temperatures. In another study it was reported that the yield strength (YS) and ultimate tensile strength (UTS) of 6111 Al alloy can be significantly enhanced by modifying the alloy with a small amount of Zr and controlling a suitable heat treatment [99].…”

Transformation characteristics of Al–Ag and Al–Ag–Ti alloys

“…The effect of additions of small amounts of zirconium and titanium to Al-1 wt%Si alloy via creep test, a sound stabilization effect of Zr and Ti on the ageing characteristics was noticed [12] and generally, Zr and Ti addition reduced the rate of creep.…”