A New Ultra-High-Strength AB83 Alloy by Combining Extrusion and Caliber Rolling

Abstract

An exceptionally high-strength rare-earth-free Mg–8Al–3Bi (AB83) alloy was successfully fabricated via extrusion and caliber rolling. After three-pass caliber rolling, the homogenous microstructure of the as-extruded AB83 alloy was changed to a necklace-like bimodal structure consisting of ultra-fine dynamic recrystallized (DRXed) grains and microscale deformed grains. Additionally, both Mg17Al12 and Mg3Bi2 nanoprecipitates, undissolved microscale Mg17Al12, and Mg3Bi2 particles were dispersed in the matrix of caliber-rolled (CRed) AB83 alloy. The CRed AB83 sample demonstrated a slightly weakened basal texture, compared with that of the as-extruded sample. Consequently, CRed AB83 showed a tensile yield strength of 398 MPa, an ultimate tensile strength of 429 MPa, and an elongation of 11.8%. The superior mechanical properties of the caliber-rolled alloy were mainly originated from the combined effects of the necklace-like bimodal microstructure containing ultra-fine DRXed grains, the homogeneously distributed nanoprecipitates and microscale particles, as well as the slightly modified basal texture.

A Superior High-Strength Dilute Mg-Bi-Ca Extrusion Alloy with a Bimodal Microstructure

“…However, the increase in cost caused by RE addition is a major obstacle to their commercial application. In order to promote application, some new low-cost, high-strength RE-free Mg alloys, such as Mg-Al- [7,8] and Mg-Sn-based [2,9] alloys, have been fabricated. Pan et al developed an Mg-2Sn-2Ca (TX22, all compositions quoted in this work are in wt.%) alloy [9] with very fine grains exhibiting an ultra-high tensile yield strength (TYS) of 443 MPa.…”

A New Extruded Mg-6Bi-3Al-1Zn Alloy with Excellent Tensile Properties

“…Furthermore, the AGS of the BAZ631 alloy is only 0.3-3 µ m, which is smaller than that of Mg-6Bi (B6) extruded under similar conditions [7], demonstrating that 3 wt.% Al and 1 wt.% Zn addition can further refine the microstructure. Generally, the size, spacing, and fraction of second particles in the BAZ631 alloy can either promote or hinder DRX in various circumstances during extrusion [20][21][22]. There are both ultra-fine Mg 3 Bi 2 precipitates and micro-scale Mg 3 Bi 2 particles in the BAZ631 sample.…”