Microstructure and Thermal Stability of A357 Alloy With and Without the Addition of Zr

Abstract

The principal purpose of this research was to evaluate the effects of Zr on the microstructure and thermal stability of an A357 alloy that has been subjected to an aging treatment (T6) and thermal exposure (250 °C). The results show that the addition of Zr had a significant influence on the refinement of the grain size, which enhanced the hardness and tensile strength of the A357 alloy under the T6 condition. During thermal exposure at 250 °C, the rodlike metastable bÕ-Mg 2 Si precipitates transformed into coarse equilibrium phase b-Mg 2 Si precipitates, resulting in a significant drop in the hardness and tensile strength of the T6 heat-treated A357 alloy. However, after thermal exposure, coherent, finely dispersed Al 3 Zr precipitates were found to be formed in the T6 heat-treated A357 alloy. The addition of 0.1% Zr played a critical role in improving the high-temperature strength. Consequently, the A357 alloy with the addition of Zr demonstrated better mechanical properties at room temperature and high temperature than the alloy without Zr, in terms of both microstructure and thermal stability.

Synergy of multiple precipitate/matrix interface structures for a heat resistant high-strength Al alloy

“…As shown in Fig. 1a, compared with the various aluminum alloys thermally exposed at different temperatures for 100 h 4,6,8,[35][36][37][38][39][40][41][42][43][44][45][46][47] , the currently designed alloy shows the best combination of strength and heat resistance after thermal exposure. It reaches a strength retention ratio (the ratio between the yield strength values of an alloy after and before a thermal exposure) of 97% and the highest residual yield strength of 400 ± 5 MPa ever reported for Al alloys thermally exposed at 200 °C for 100 h. This means the designed alloy overcomes the trade-off between heat resistance and strength for different types of aluminum alloys.…”

“…Fig.1| Mechanical properties and size stability of precipitates of the current Al-4Cu-0.315Mg-0.5Ag-0.21Si-0.09Sc alloy. a Yield strength (superscript* for tensile strength) of different Al alloys thermally exposed at different temperatures for 100 h4,6,8,[35][36][37][38][39][40][41][42][43][44][45][46][47] and corresponding strength retention rates, more details can be found in Supplementary Table1. b, c Typical images used to measure the diameter and thickness of θ′-Al 2 Cu precipitates in the peak-aged state of the current alloy.…”

Current Progress in Rheoforming of Wrought Aluminum Alloys: A Review

“…Thermal conductivity of some common Al alloys fabricated by conventional casting and rheoforming[115,116,[120][121][122][123][124].…”