Effect of long term aging on the microstructural stability and mechanical properties of Ti-6Al-2Cr-2Mo-2Sn-2Zr alloy
Effect of long term aging on the microstructural stability and mechanical properties of Ti-6Al-2Cr-2Mo-2Sn-2Zr alloy
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DOI：
10.1016/s0921-5093(02)00448-3
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发表时间：
2003-03-15
期刊：
影响因子：
6.4
通讯作者：
Fraser, HL
中科院分区：
文献类型：
--
作者：
Zhang, XD;Evans, DJ;Fraser, HL
研究了Ti-6Al-2Cr-2Mo-2Sn-2Zr合金长期时效后的组织发展及其对力学性能的影响。四种类型的合金沉淀已确定,他们是α(2)-Ti3Alω、硅化物和alpha-TiCr2洗涤阶段。在接收材料和所有时效样品中均观察到α (2)-Ti3Al和ω。硅化物（Ti, Zr）(x) Si-3（5小于或等于x小于或等于6）在550 ~ 650℃时效500 h的样品中发现。硅化物具有六边形结构，晶格参数为：a = 7.01 +/- 0.03, c = 3.63+/-0.06埃。硅化物与母体β相的取向关系为：[111]β //[0001]（硅化物），（101）(β)//(1100)（硅化物）。在450 ~ 550℃时效500h的样品中观察到α -(Ti, Zr)Cr-2相。它具有立方结构（a=7.12+/-0.03埃），与α -和β - ti矩阵的取向关系为：[110](α - ticr2)//[0001](α - ti)//[110](β - ti), ((1) / bar 13)(α - ticr2)//((1) / bar 100)（β - ti）。在450 ~ 550℃的温度范围内长期时效，由于α (2)- ti3al和α -(Ti, Zr)Cr-2 Laves相的析出，导致断裂韧性降低，晶间破坏增加。尽管α (2)-Ti3Al和硅化物析出，但在650℃时效至1000 h时，试样的断裂韧性没有明显变化。在这些温度下时效后断裂韧性的保留归因于时效处理过程中次生α - ti血小板的粗化。(C) 2002 Elsevier Science B.V.版权所有
Microstructural development after long term aging and its effect on the mechanical properties have been investigated in Ti-6Al-2Cr-2Mo-2Sn-2Zr alloy. Four types of precipitates have been identified in the alloy, they are alpha(2)-Ti3Al, omega, silicides and alpha-TiCr2 Laves phase. alpha(2)-Ti3Al and omega are observed in the as-received materials and all aged samples. Silicides, (Ti, Zr)(x) Si-3 (5 less than or equal to x less than or equal to 6), are found in the specimens aged at 550-650 degreesC over 500 h. The silicides have a hexagonal structure with a lattice parameter: a = 7.01 +/- 0.03, c = 3.63+/-0.06 Angstrom. The orientation relation between the silicides and the parent beta-phase has been determined as: [111]beta//[0001](silicide), (101)(beta)//(1100)(silicide). Laves phase alpha-(Ti, Zr)Cr-2 is observed in the samples aged at 450-550 degreesC over 500h. It has a cubic structure (a=7.12+/-0.03 Angstrom) with an orientation relationship with the alpha- and beta-Ti matrix: [110](alpha-TiCr2)//[0001](alpha-Ti)//[110](beta-Ti), ((1) over bar 13)(alpha-TiCr2)//((1) over bar 100)(beta-Ti). Longterm aging in the temperature range of 450-550 degreesC results insignificant decrease of fracture toughness and increase of intergranular failure, due to precipitation of alpha(2)-Ti3Al and alpha-(Ti, Zr)Cr-2 Laves phase. No considerable change in fracture toughness for the samples aged at 650 degreesC up to 1000 h is found in spite of precipitation of the alpha(2)-Ti3Al and the silicides. The retention of fracture toughness after aging at these temperatures has been attributed to coarsening of secondary alpha-Ti platelets during the aging treatment. (C) 2002 Elsevier Science B.V. All rights reserved.