The Microstructure and Mechanical Properties of the Ball-Milled and Hot Press-Sintered Al–Mn–Ce–Zr Alloy
摘要
The evolution of the microstructure and mechanical properties of Al–Mn–Ce–Zr alloy during high-energy ball milling and hot press sintering was studied in order to develop a light alloy with increased strength at room and elevated temperatures. The solidification-induced λ-Al4Mn, Al20Mn2Ce, α-Al11Ce3, and D023-Al3Zr phases were refined and dissolved during milling. High-energy ball milling provided a nanostructured supersaturated solid solution with a grain size of ~ 20 nm, and Mn-rich phases were replaced by the Al6Mn phase with precipitate sizes of ~ 10 nm. Ce-rich phases facilitated Mn-rich phase dissolution and precipitation kinetics. The Mn solute content reached ~ 2–3 at pct after milling for ~ 10 hour. The Al-enriched precipitation-depleted zones were formed at the periphery of powder particles during hot press sintering at 450 °C and provided for a high consolidation degree and a low porosity. This treatment led to the precipitation of the fine Al6Mn, α-Al11Ce3, and D023-Al3Zr phase precipitates, which inhibited grain growth and provided a mean grain size of ~ 60 nm at elevated temperature. Due to the nanostructured matrix and the fine precipitates, the sintered alloy exhibited advanced compression strength properties with a yield strength of ~ 720 MPa, an ultimate compression strength of ~ 810 MPa, a strain to failure of ~ 2.3 pct at room temperature, and a yield strength of ~ 290 MPa at elevated deformation temperature of 350 °C.