Characterization of Hot Deformation Behavior of a Novel Al–Cu–Li Alloy Using Processing Maps

Abstract

The isothermally compression deformation behavior of an elevated Cu/Li weight ratio Al-Cu-Li alloy was investigated under various deformation conditions. The isothermal compression tests were carried out in a temperature range from 300 to 500°C and at a strain rate range from 0.001 to 10 s -1 . The results show that the peak stress level decreases with temperature increasing and strain rate decreasing, which is represented by the Zener-Hollomon parameter Z in the hyperbolic sine equation with the hot deformation activation energy of 218.5 kJ/mol. At low Z value, the dynamic recrystallized grain is well formed with clean high-angle boundaries. At high Z value, a high dislocation density with poorly developed cellularity and considerable fine dynamic precipitates are observed. Based on the experimental data and dynamic material model, the processing maps at strain of 0.3, 0.5 and 0.7 were developed to demonstrate the hot workability of the alloy. The results show that the main softening mechanism at high Z value is precipitate coarsening and dynamic recovery; the dynamic recrystallization of the alloy can be easily observed as ln Z B 29.44, with peak efficiency of power dissipation of around 70%. At strains of 0.3, 0.5 and 0.7, the flow instability domains are found at higher strain rates, which mainly locate at the upper part of processing maps. In addition, when the strain rate is 0.001 or 0.02 s -1 , there is a particular instability domain at 300-350°C.

Finite Element Modeling on the Compaction of Copper Powder Under Different Conditions

“…In PM production, powder cold compaction in the die is one of the most important steps because a high performance compact with high relative density, uniform density and stress distributions can not only simplify the subsequent processes such as sintering and finishing but also produce the part with superior quality and property and low cost. [1][2][3] Therefore, numerous studies either physically or numerically were carried out in this regard for powder cold die compaction, [3][4][5][6][7][8][9][10][11][12][13] whereas most of which were focusing on the forming of powders with relatively low initial packing density. Actually, die filling in the PM production is also a critical step; researchers have realized that high relative density and homogeneity in initial powder packing formed during die filling are of key importance for subsequent procedures.…”

Enhanced High-Temperature Mechanical Properties of Al–Cu–Li Alloy through T1 Coarsening Inhibition and Ce-Containing Intermetallic Refinement

“…Master alloys of Al–Cu (50 wt%), Al–Zr (3.29 wt%), Al–Ce (10 wt%), and pure Ag, Mg, Li, and the remaining Al were melted in a vacuum induction melting furnace in a controlled Ar gas atmosphere, in a high-purity graphite crucible [1]. The casting was performed in Ar, using a Cu mold surrounded by cooling water [27]. The ingots were homogenized through a two-step homogenization course at 470 °C, 8 h and 510 °C, 16 h in a salt bath, followed by air cooling.…”

Improved Recrystallization Resistance of Al–Cu–Li–Zr Alloy through Ce Addition

“…Master alloys of Al-Cu, Al-Zr, Al-Ce, and pure Ag, Mg, Li, and the remainder Al were melted in a vacuum induction melting furnace in a controlled Ar gas atmosphere, in a high-purity graphite crucible. Casting was performed under Ar, using a Cu mold surrounded with cooling water [23]. The as-cast ingots were homogenized in two stages, at 470 • C/8 h and 510 • C/16 h in a salt bath, followed by air cooling to room temperature.…”