| Mechanical alloying of rapidly solidified 2024 Al alloy and commercial SiC₁ powders has been studied by using a high energy ball mill. The 3 wt.% methanol as a milling agent, has been added to maintain a balance between cold welding and fracturing. Mechanical alloying proceeds by the continual cold welding and fracturing of the constituent powder particles when subjected to the large compressive forces between steel balls. The steady-state processing condition, i. e., an equiaxed particles, an uniform powder size distribution and a saturation hardness signifying the completion of MA, has been reached at the attrition velocity 150rpm and MA time more than 300min. The MA powders were produced by cold pressing, degassing and hot extrustion, and their microstructures and hardness were investigated. Isochronal annealing experiment revealed that thermal stability was high at temperature up to 350℃ On the other hand, the aging hardenability of these alloys was lower than rapidly solidified 2024 Al alloy. |
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