| 摘要: | 本研究藉由顯微結構觀察、腐蝕性質不同溫度的退火處理與機械性質試驗等，探討Fe、Mn對Al-5.0Mg鍛造型鋁合金再結晶、機械性質與腐蝕性的影響。
結果顯示，隨著合金中Fe含量上升，在加工過程中容易堆積差排的富鐵相也將增加，退火後合金再結晶率將上升，使晶粒粗化，進而損害合金強度，此外，富鐵相還被發現對延性有不良影響。而隨著Mn含量上升，合金晶粒內將產生細小的Al6Mn顆粒，Al6Mn能夠阻擋退火時的差排與晶界移動，抑制合金再結晶，進而細化晶粒，達到細晶強化的效果，另外，細小的Al6Mn本身也具有散佈強化的效果，使得合金強度提升明顯。
另外，隨著Mn含量上升，合金晶粒尺寸下降，β相(Mg2Al3)在晶界上將由不連續轉為連續析出，因而損害合金抗腐蝕性;而隨著Fe含量上升，低Mn合金晶粒將細化，而高Mn合金晶粒尺寸則無明顯差異，表示Fe元素對合金抗腐蝕性無正面影響。
綜上結果發現，含高Mn且低Fe之合金，具最佳機械性質及最細晶粒尺寸，但抗腐蝕性較差，而含低Mn低Fe合金，具較差機械性質及最粗晶粒尺寸，但腐蝕性最佳。
;This study explored the effects of Fe and Mn on the recrystallization, mechanical properties and corrosivity of Al-5.0Mg forged aluminum alloy by microstructure observation, annealing treatment at different temperatures for corrosion properties, and mechanical property tests.
The results show that as the Fe content in the alloy increases, the iron-rich phase that is easy to accumulate during processing will also increase, and the alloy recrystallization rate will increase after annealing, which will coarsen the grains and damage the strength of the alloy. In addition, the iron-rich phase has also been found to have an adverse effect on ductility. As the Mn content increases, fine Al6Mn particles will be produced in the alloy grains. Al6Mn can block the shift and grain boundary movement during annealing, inhibit the alloy recrystallization, and then refine the grains to achieve the effect of fine grain strengthening. In addition, The fine Al6Mn itself also has the effect of dispersion strengthening, which makes the alloy strength increase significantly.
In addition, as the Mn content increases, the alloy grain size decreases, and the β phase (Mg2Al3) will change from discontinuous to continuous precipitation at the grain boundary, thus impairing the corrosion resistance of the alloy; and as the Fe content increases, the low Mn alloy grain size may be fine.The grain size of the high Mn alloy will be refined, and there will be no significant difference in the grain size of the high Mn alloy, indicating that Fe has no positive effect on the corrosion resistance of the alloy.
Based on the above results, it is found that alloys containing high Mn and low Fe have the best mechanical properties and the finest grain size, but poor corrosion resistance, while alloys containing low Mn and low Fe have poor mechanical properties and the coarsest grain size , but have the best corrosion resistance. |
