Compressive creep behaviour of Mg–Li–Al alloy

Abstract

The compressive creep behaviour of as cast Mg214Li21 . 3Al (wt-%) alloy was investigated in the temperature range of 20285uC and under different compressive stress in the range of 37 . 3-74 . 6 MPa with special apparatus. Primary creep deformation and steady creep rate increase with temperature and applied stress. The compressive creep behaviour obeys an empirical equation ln t5C2nln szQ/RT, where t is the time to a selected creep strain, s is the applied stress, T is the absolute temperature, R is the gas constant, and C, n, and Q are constants for the experimental alloy. The average values of the exponent n and the creep activation energy Q are 4 . 33 and 101 . 13 kJ mol 21 respectively. The creep rate controlling mechanism is the dislocation climb and the lattice diffusion of Li in the experimental alloy under the testing conditions.

Effect of Li content on the indentation creep characteristics of cast Mg–Li–Zn alloys

“…The slope of the fitted lines is Q/R, from which the average activation energies of 90.0, 91.7 and 98.2 kJ/mol were obtained for the LZ41, LZ81, and LZ121 alloys, respectively. These activation energies, which are tabulated in Table 2, are in agreement with Q = 101 kJ/mol, Q = 103 kJ/mol , and Q = 89.4 kJ/mol reported, respectively, for compressive creep of the cast Mg-14Li-1.3Al alloy [9], tensile creep of Mg-9Li alloy [17], and high-temperature tensile deformation of Mg8Li-2Zn alloy [21].…”

“…The LZ41 alloy with the lowest a-values in the range of 0.148-0.187 is more creep resistant than the LZ81 and LZ121 alloys with higher a-values of 0.195-0.350 and 0.226-0.367, respectively.The obtained average stress exponent values, also included inTable 2, are about 7.0, 4.5, and 4.2 for the LZ41, LZ81, and LZ121 alloys, respectively. It is worth noting that the conventional compressive creep tests on a cast Mg-14Li-1.3Al alloy[9] has shown an average stress exponent of 4.33, which is close to our n-values of 4.5 and 4.2 for the alloys with high Li levels. In another work, stress exponent of 5 has been reported for the tensile creep of an as-cast Mg-9Li alloy in the temperature range of 423-523 K[17].…”

“…The compressive creep study of a cast Mg-14Li-1.3Al alloy has yielded average stress exponent and activation energy of 4.3 and 101 kJ/mol, respectively. Accordingly, the creep rate controlling mechanism of dislocation climb and lattice diffusion of Li has been suggested [9]. Recently, the effect of Ca addition on the creep behavior of an extruded Mg-5Li-3Al alloy has been examined in the temperature range of 373-423 K [10].…”

A 3-D Mathematical Model of Thermal Field Evolution in the Direct Chill Casting of Superlight Magnesium Alloy Slabs

“…As the lightest alloys among the known metals and alloys, Mg-Li alloys (the density between 1300 and 1600 kg/m 3 ) have high specific stiffness and excellent ductility at low temperatures. So they have been attractively investigated and have the application potential in the fields of aerospace, aircraft structures, automobile and electric industry as well as for structural components in ultra-light communication systems [1][2][3][4] .…”

“…The general mechanical properties of Mg-Li-x alloys have been extensively investigated [7][8][9][10] . The commercial magnesium alloy, LA141, containing 14wt% Li and 1wt% Al, has been considered for space applications, and it presents good mechanical properties [1] . However there is few reported work on the processing of Mg-Li alloys.…”