Effect of heat treatment and silicon addition on the microstructure development of Ti-6Al-2Cr-2Mo-2Sn-2Zr alloy
Effect of heat treatment and silicon addition on the microstructure development of Ti-6Al-2Cr-2Mo-2Sn-2Zr alloy
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DOI：
10.1016/s0921-5093(02)00381-7
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发表时间：
2003-02-25
期刊：
影响因子：
6.4
通讯作者：
Cornell, B
中科院分区：
文献类型：
--
作者：
Zhang, XD;Bonniwell, P;Cornell, B
研究了Ti-6-22-22-0.22Si和Ti-6-22-22-0.02Si在β、α/β和时效热处理后的显微组织发展。在β热处理后测定初级α形态。发现β处理的冷却速率显著影响HCP转变产物，范围从速率超过5.5 ℃ s（-1）的主要α ′马氏体和针状α，到中等冷却速率的魏氏组织和α菌落的混合物，到最慢速率0.27和0.055 ℃ s（-1）的α菌落。不同的冷却速率从α/β热处理显着影响保留的β相和二次α的微观结构中的体积分数。更高的冷却速率导致β相的更大保留和在老化时该相转变成二次α。这种更高量的细的次级α相促进了更高的强度和更低的韧性。α/β热处理温度显著影响显微组织的热处理响应。高的热处理温度促进更大量的保留β与精细，转化α在最终的微观结构。较低的α/β热处理温度促进保留β微观结构，其对时效处理的响应较小。老化处理促进保留的β相的分解，特别是在较大的保留β区域，表现出较低的稳定性。热处理高硅和低硅合金的显微组织特征在大多数情况下是相同的。然而，在593 ℃时效后，在高Si合金中观察到非常细的硅化物，这可能对断裂韧性具有显著影响。(C)2002 Elsevier Science B. V.保留所有权利。
Microstructural development of Ti-6-22-22-0.22Si and Ti-6-22-22-0.02Si after beta, alpha/beta, and aging heat treatment was investigated. Primary alpha morphology was determined following beta heat treatment. Cooling rate from beta treatment was found significantly influence the HCP transformation products, ranging from principally alpha-prime martensite and acicular alpha at rates exceeding 5.5 degreesC s(-1), to mixtures of Widmanstatten and colony alpha at intermediate cooling rate, to colony alpha at the slowest rates of 0.27 and 0.055 degreesC s(-1). Varying cooling rates from the alpha/beta heat treatment significantly influenced the volume fraction of retained beta phase and secondary alpha in the microstructure. Higher cooling rate resulted in greater retention of the beta phase and transformation of the phase into secondary alpha upon aging. This higher amount of fine, secondary alpha phase promoted higher strength and lower toughness. Alpha/beta heat treatment temperature significantly influenced the heat treatment response of the microstructure. High heat treatment temperatures promoted greater amounts of retained beta with fine, transformed alpha in the final microstructures. Lower alpha/beta heat treatment temperatures promoted retained beta microstructures which were less responsive to aging treatment. Aging treatment promoted decomposition of retained beta phase, particularly in larger retained-beta regions that exhibited lower stability. Microstructural characteristics of heat treated high and low Si alloys appears identical in most cases. However, very fine silicides were observed in the high Si alloy after aging at 593 degreesC, which may have a significant effect on fracture toughness. (C) 2002 Elsevier Science B.V. All rights reserved.