High-temperature wear and friction properties of ZE41 alloy were evaluated using a pin on disc tribometer. The microstructure of the alloy has the equiaxed grains of 72±20µm decorated with the rare earth rich precipitates. Result shows that wear rate decreases upto 100°C and then increases until 250°C for all the loading conditions. The wear mechanism study revealed that the underlying thin oxide tribolayer minimizes the wear rate upto 100°C. Above 100°C, thickening of oxide layer due to enhanced oxidation rate results in breakage of the layer. Further, the increase of temperature softens the alloy which deforms and fractures in the subsurface at low critical load resulting in more delamination wear. The combined effects of oxidation and delamination wear are accentuated with the increase of load and temperature resulting in the increase of the wear rate. Comparing the influence of load and temperature on the wear rate, contact load is more.
A commercial ZE41 Mg alloy was processed by equal channel angular pressing (ECAP) using route BC (90o sample rotation after each pass) and route C (180o sample rotation after each pass) at 250, 300 and 350 oC for up to 4 passes. Significant grain refinement from ∼150 μm to ∼33 μm occurred at the higher third and fourth ECAP passes. The most effective process among all routes and temperature combinations was via route C at 250 oC. Nearly 83% increase in yield strength, 58% increase in ultimate tensile strength, and 107% increase in fracture strain were observed after 4 ECAP passes using route C at 250 oC. The increase in the strength of the alloy was attributed to grain refinement during static and dynamic recrystallization. Fractography of tensile samples showed that shallow dimples change to fine dimples at higher passes modifying the failure mode from cleavage to ductile fracture.
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