THE EFFECT OF NB, TI, AL ON PRECIPITATION AND STRENGTHENING BEHAVIOR OF 718 TYPE SUPERALLOYS
THE EFFECT OF NB, TI, AL ON PRECIPITATION AND STRENGTHENING BEHAVIOR OF 718 TYPE SUPERALLOYS
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NB、TI、AL对718型高温合金析出及强化行为的影响
DOI：
10.7449/2005/superalloys_2005_287_298
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发表时间：
2005
期刊：
影响因子：
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通讯作者：
T. Carneiro
中科院分区：
文献类型：
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作者：
X. Xie;J. Dong;G. Wang;W. You;J. Du;C. Zhao;Z. Wang;T. Carneiro
Inconel 718具有独特的力学性能，在各种高温行业中有着广泛的应用。而718合金的上限温度为650 ℃，这是由于主强化相γ″-Ni 3（Nb，Ti，Al）的不稳定性造成的。在高温下，亚稳γ″转变为大尺寸、片状的稳定相δ-Ni 3 Nb。结果表明，718合金的组织稳定性和强化效果均有所下降。近年来，许多研究人员对718合金的稳定性进行了研究，并试图开发出适用于650以上的718合金。本文的基本思想是通过提高γ″和γ′的固溶温度、减缓δ-Ni 3 Nb的γ″相变以及改变γ″/γ′相的析出行为来提高γ″和γ′强化相的稳定性。本研究准备了实验炉，研究了718合金基本化学成分中Nb、Ti、Al及其原子比的变化。用扫描电镜和透射电镜研究了γ″和γ′相的析出行为，用电解分离和显微化学分析方法准确测定了γ″+γ′相的质量分数。测试了不同炉次的硬度、拉伸性能和持久性能。- 还采用了新开发的718型Alloy Allvac ® 718 Plus TM的结构进行比较。对718型高温合金的组织稳定性和强化效果进行了详细的讨论。
Inconel 718 characterizes with unique mechanical properties and has wild application in different high temperature industries. However, the ceiling temperature for Alloy 718 is 650 because of ℃ the instability of main strengthening phase γ″-Ni3(Nb,Ti,Al). At high temperatures the metastable γ″ changes for stable phase δ-Ni3Nb with large size and plate- like morphology. In result of that Alloy 718 looses structure stability and strengthening effect. Recently, many researchers have studied the stability of Alloy 718 and try to develop modified 718 Alloys to be used beyond 650 . The basic idea of this paper is to raise the stability of ℃ γ″ and γ′ strengthening phases in the following ways: raising the solution temperature of γ″ and γ′, retarding the γ″ phase change for δ-Ni3Nb and changing the precipitation behavior of γ″/γ′ phase. The experimental heats were prepared for this study in variation of Nb, Ti, Al and the atomic ratio among them on the base chemical composition of Alloy 718. The precipitated phase γ″ and γ′ behavior was studied in detail by means of SEM and TEM and the weight fraction of γ″+γ′ phases was exactly determined by electrolytic isolation and followed by micro-chemical analyses. The mechanical properties including hardness, tensile properties and stress rupture for several heats were also tested. － The structure of a new developed 718 type Alloy Allvac ® 718 Plus TM has been also adopted for comparison. A detail discussion has been conducted for 718 type superalloys in structure stability and strengthening effect both.