Microstructure and Mechanical Properties of Mechanically Alloyed Al-Mn-Cu-Zr Alloy

Abstract

Development of materials and processing regimes for the enhancement of specific strength is a challenge for the aviation, aerospace and transportation industries. The paper analyzes the evolution of microstructural parameters and mechanical properties of the Al – 5 %Zr – 4 %Mn – 2 %Cu alloy obtained by mechanical alloying with subsequent hot pressing at temperatures between 350 and 450°C. High-energy ball milling for 10 h formed nanostructured granules of aluminum-based solid solution with the grain size of 20–30 nm and microhardness of ~460 HV. After hot pressing and further annealing, grains increased up to ~90 nm, the Al₃Zr, Al₆Mn and Al₂₀Cu₂Mn₃ phases precipitated and the formation of zones free from secretions along the boundaries of the granules. The microhardness of granules after annealing to the compaction temperature decreased to ~300–340 HV, and the hardness of hot-pressed specimens did not exceed 280 HV, which was attributed to residual porosity. The lowest porosity (0.5 %) was found in specimens consolidated at 450°C, the compressive yield stress of which reached ~700 MPa at room temperature and ~170 MPa at 350°C.