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題名 | βCuZn合金的相變態 |
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作者 | 徐永富; 王文雄; | 書刊名 | 材料科學 |
卷期 | 23:2 1991.06[民80.06] |
頁次 | 頁189-202 |
分類號 | 440.39 |
關鍵詞 | βCuZn合金; 相變態; |
語文 | 中文(Chinese) |
中文摘要 | 本實驗針對含Zn量38~40wt之βCuZn合金,探討利用不同的熱處理方 式,對於合金相變態之影響,並分析其顯微結構。實驗結果顯示,合金成份及冷 卻速率對相變態有很大之影響。在稍慢的冷卻速率時,αw相為主要的析出相, αm相則主要在α單相區的成分範圍及較快的冷卻速率下形成。當Zn含量增加 時,則愈容易抑制α相的析出。 准安定β'經深冷處理產生二階段的麻田散體變態。較高溫形成的是熱彈性型的 麻田散體;在較低溫度形成的雖是burst type的麻田散體,但仍具有熱彈性之特性, 因其在逆變態時之溫度遲滯很小,其結構為M9R,內部之缺陷為在(001)基底面形 成的疊差。而這二種麻田散體在加熱時其逆變態反應是完全可逆的。 β'相經恆溫時效處理會析出α1-plate,其最初形成時之結構為9R,內部之次結構 為在(001)基底面形成之疊差。隨時效時間增長,其板片大小與數量顯著增加,而 其結構則由9R逐漸轉變為FCC結構,疊差的密度亦顯著減少,甚至完全消失,而 其界面也由平整狀態變為較不規則的外觀。 |
英文摘要 | The effects of various heat treatments on phase transformation of βCuZn alloys containing 38-40wtVo Zn were investigated by electrical resistivity measurements as well as by OM and TEM examinations. The results show that the alloy composition and the cooling rate are the two most important factors which affect the phase transformation. Under a slower cooling rate, αw phase is the predominantprecipitate. However, αw, phase is the major precipitate under a faster cooling rate with compositions lyinginside the single-phase a field. The precipitation of a phase can be inhibited easily when the zinc contentof the alloy is above 39 wtVo. . Two types of martensites are formed from metastable β' phase during sub-zero cooling. The bandedmartensites are formed at a higher sub-zero temperature, which show a thermoelastic nature and growslowly in the lengthwise direction. At a lower sub-zero temperature, the parallelogram-shaped martensites with M9R type LPSO (long period stacking order) structure are abruptly formed in a burst manner,which show a thermoelastic nature also. Both martensites can be transformed to parent β' phase reversibly and completely upon heating to room temperature with a small temperature hysteresis. The internaldefects of martensites are found to be the stacking faults on (001) basal plane. The crystal structures of ai-plates formed in the early stage of 250℃ aging are identified as a 9RLPSO structure, and the stacking faults inside the plates are on the (001) basal plane. When againg proceeds, the amount and the size of α1-plate increase, the crystal structures of α1-plates gradually changefrom 9R type of FCC structure, and the density of stacking faults in the α1-plates decreases gradually.Eventually, the stacking faults disappear and the interface between α 1-plate and β' phase becomes moreirregular with a longer aging time. |
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