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NiAl介金屬化合物與其他超合金相比較，具有低密度、高融點、高強度
以及較佳的抗氧化性等優點，因此成為航太工業上深具潛力的結構材料。
前人曾利用粉末預先氧化方法與控制晶粒大小的方法製成NiAl/Al2O3複合
材料，該複合材料具有優於NiAl者的機械性質與高溫強度。為繼續瞭解
NiAl材料及NiAl/Al2O3複合材料在高溫時的氧化行為，本研究利用前述二
種方法製成NiAl/Al2O3複合材料，檢討預先氧化的溫度和晶粒的尺寸對於
該材料在1000℃/24h長時間高溫氧化的影響。 本研究主要以熱重分析儀
（Thermogravimetric analyzer，TGA）進行實驗，以檢測試樣在高溫氧
化時之重量增加量與增重的速率，來評定該試樣的抗氧化性質是否良好。
實驗結果顯示，NiAl/Al2O3複合材料的高溫氧化行為可分為二階段進行：
氧化開始後的十小時間，NiAl/Al2O3複合材料表面形成氧化膜的速率（即
熱重曲線的斜率）較快，十小時以後的第二階段，因氧化膜逐漸長成緻密
的保護膜使得氧化速率減緩。NiAl粉末經過適當的預先氧化而製成的
NiAl/Al2O3複合材料，其氧化速率低於NiAl材料。在本實驗中，經過分級
為7mm的NiAl粉末，再以650℃/2h預先氧化後，形成的NiAl/Al2O3燒結體
有最佳的抗氧化性。 另一方面，由於NiAl的價格較為昂貴，為降低製作
NiAl/Al2O3複合材料的成本，吾人亦嘗試以較為廉價的Ni、Al元素粉末與
強化用的Al2O3粉末為起始原料，利用反應燒結的方式來合成NiAl/Al2O3
複合材料。此實驗是藉由製程條件的改變，以尋求一個最佳的反應燒結製
程。實驗結果顯示，以2atm的Ar氣氛、15℃/min昇溫速度進行反應燒結，
所得的NiAl/Al2O3燒結體之形狀與緻密性，會比在真空下、以5℃/min昇
溫速率進行反應燒結的燒結體來的好。 然而，以反應燒結製成的最佳
NiAl/Al2O3燒結體，其相對密度僅有89.8％，導致其機械性質與抗氧化性
並不好，甚至遠低於以預先氧化法製成的緻密燒結體的性質。
Compared with other superalloys, Nickel aluminide compound
(NiAl) has many advantages such as low density, high melting
point, high strength, and excellentoxidation resistance.
Therefore, NiAl is the most potential material for application
in aerospace industry. Some works have been done by using of the
methods of powder pre-oxidation and controlling grain sizes to
prepare NiAl/Al2O3 composites, which have better mechanical
properties and elevated temperature strength than that of NiAl.
To understand continuous the monolithicof NiAl and understand
the oxidation behavior of NiAl/Al2O3 composites at high
temperatures, two methods prescribed above are used to produce
the monolithic NiAl and NiAl/Al2O3 composites. Then, the effects
of pre-oxidation and controlsof grain size on the oxidation
behavior of monolithic NiAl and NiAl/Al2O3 composites at 1000℃
for 24h are investigate. The thermogravimetric analyzer is used
to determined the weight gain and the oxidation rate of NiAl/Al2
O3 composites. The results show that two stages can beobserved
in the oxidation behavior of NiAl/Al2O3 composites. In the first
stage of initial ten hours, oxides formed on the surface of
NiAl/Al2O3 composites increases with oxidation time. In the
second stage, the oxidation rate becomes slower as result of
formation of the dense protective layer. The oxidation rate of
the NiAl/Al2O3 composites is lower than that of NiAl. In this
study, the NiAl/Al2O3 composite prepared from 7 micrometer NiAl
powder and pre-oxidized at 650℃/2h has the best oxidation
resistance. On the other hand, for reducing the production
cost, the syntheses NiAl/Al2O3 composites with cheaper Ni, Al
and Al2O3 powders by the reactive sintering method are
investigated in this study. The result shows that the shape and
density of the reactive sintered NiAl/Al2O3 composite
synthesized in 2 atm Ar atmosphere and in a heating rate 15℃/
min. to 1450℃ is better than that composites synthesized in
vacuum and in a heating rate of 5℃/min. to 1400℃. However,
the relative density of the best reactive-sintered NiAl/Al2O3
composites is only 89.8%, which makes the mechanical and the
oxidation properties decrease.Key Words: NiAl, NiAl/Al2O3
composites, oxidation, synthesis
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