|Spoluautoři ČAPEK Jaroslav, VOJTĚCH Dalibor|
Mechanical alloying has been becoming widely used method for preparation of metallic materials. Its advantage lies in the possibility of obtaining amorphous or nanostructured material. However, there are problems connected with the compacting of prepared powder materials, during which coarsening of the microstructure occurs. Spark plasma sintering (SPS) may be a potential solution. It is a very fast method preventing grain coarsening and maintaining the structure very fine which leads to high mechanical properties. We used combination of these two methods to prepare Mg-Zn alloy containing 50 wt.% of zinc. Powders of pure magnesium and zinc were milled in a planetary ball mill for different times. One selected sample was subsequently compacted by SPS. Microstructure, phase composition, short-term thermal stability and hardness were examined in detail. After 8 hours of milling, the powder consisted of very fine and homogeneously distributed Mg and metastable Mg7Zn3 phases. During the SPS compacting Mg7Zn3 phase decomposed into new phases Mg, MgZn, MgZn2 and Mg2Zn11. Short-term annealing at temperatures of 100, 200 and 300 °C did not show any differences in the phase composition. With rising annealing temperature hardness of the compacted sample (260 HV5) regularly decreased.