Effect of microstructure on the high-temperature deformation behavior of Nb-Si alloys
Effect of microstructure on the high-temperature deformation behavior of Nb-Si alloys
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DOI：
10.1016/j.msea.2008.04.123
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发表时间：
2009-06
期刊：
影响因子：
6.4
通讯作者：
S. Miura;Yuki Murasato;Y. Sekito;Yukiyoshi Tsutsumi;K. Ohkubo;Y. Kimura;Y. Mishima;T. Mohri
中科院分区：
文献类型：
--
作者：
S. Miura;Yuki Murasato;Y. Sekito;Yukiyoshi Tsutsumi;K. Ohkubo;Y. Kimura;Y. Mishima;T. Mohri
研究了Nb-Si-Zr合金在室温、室温和室温下的变形行为。1670K采用氩弧熔炼Nb-18.1at%Si-1.5at%Zr中间合金锭，并添加Mg。铸锭中的Nb棒（半径1μm）是在Nb 3Si基体中通过共晶反应形成的。合金在1923 K下热处理4- 100 h，通过共析反应将Nb_3Si基体分解为Nb和Nb_5Si_3，获得大Nb网络结构和细小的硅化物（α-Nb_5Si_3）颗粒。压缩测试在室温下在空气中和在高温下在Ar气氛中进行。在1471 K时，最大强度为500 MPa，压缩塑性大于10%，应变速率为1.0×10 - 4s-1，而在室温时，最大强度超过1500 MPa，压缩塑性约为1.5%。高温变形服从幂律型方程。应力指数n = 4.8，表观活化能为350 kJ/mol。室温下的维氏压痕表明，韧性Nb有效地抑制了室温下的裂纹扩展。这表明网络结构中的Nb聚集体充当包含细Nb 5Si 3颗粒的大Nb晶粒，这可能有利于低温下的延展性。
Deformation behavior of Nb–Si–Zr alloys is investigated at various temperatures ranging from R.T. to 1670K. The master alloy ingots composed of Nb–18.1at% Si–1.5at% Zr doped with Mg are Ar-arc-melted. The ingots contain Nb rods (radius: 1μm) in Nb3Si matrix formed by eutectic reaction. Alloys are subjected to heat treatments at 1923K for 4–100h to obtain a large Nb network structure with small silicide (α-Nb5Si3) particles by decomposing Nb3Si matrix into Nb and Nb5Si3through a eutectoid reaction. Compression tests are conducted at room temperature in air and at elevated temperatures in Ar atmosphere. At 1471K the maximum strength is 500MPa and compressive ductility is higher than 10% with a strain rate of 1.0×10−4s−1, while at room temperature the maximum strength is over 1500MPa and compressive ductility is about 1.5%. The high-temperature deformation obeys a power-law type equation. The stress exponent n is evaluated to be 4.8 and the apparent activation energy is 350kJ/mol. The Vickers indentation at room temperature revealed that the crack propagation at room temperature is suppressed effectively by ductile Nb. This suggests that the Nb aggregate in the network structure acts as a large Nb grain containing fine Nb5Si3particles, which might be beneficial for ductility at low temperatures.