摘要
针对在航空发动机领域具有广阔应用前景的Ti-22Al-23Nb-2(Mo,Zr)5元系合金,采用扫描电镜、透射电镜与多种力学性能实验设备,开展合金相区温度区间、β/B2锻造与热处理过程的组织演化及力学性能响应关系研究。结果表明:合金由高温至低温依次经历B2、B2+α2、B2+α2+O、B2+O四个相区,分别对应1060℃、950℃和930℃三个临界温度。β/B2锻造合金组织中B2晶界相的组成与形态受B2相的畸变强度与热处理共同作用,粗大断续的α2相易于在强畸变的原始B2相晶界形成,并在B2+O相区热处理过程中转变为α2+Orim结构;细小连续的O相易形成于弱畸变的动态再结晶B2相晶界,经B2+α2相区热处理可完全转变为α2相;静态再结晶晶界基本无晶界相。B2相晶内析出相主要受热处理影响,α2相和O相均可由B2相直接独立析出,O相也可依附α2相生成,形成α2/Orim核壳结构,表明α2相核具备良好的低温稳定性;固溶+时效处理后,基体B2相晶内均呈现由大、小两套析出相组成的混合组织,B2+α2相区固溶时为粗大α2/Orim+细小O相,B2+O相区固溶时为粗大OI+细小OII。B2晶内析出相的尺寸分布是影响力学性能的主要因素,尺寸大对合金塑、韧性有利,而对强度和蠕变抗力不利。
Quinary Ti-22 Al-23 Nb-2(Mo, Zr) alloy has a broad application prospect in the aeroengine field. The temperature ranges of phase regions, β/B2 processing, heat treatment and the corresponding mechanical properties were investigated by SEM, TEM and multi mechanical testing machines. The results show that the alloy goes through B2, B2+α2, B2+α2+O and B2+O four phase regions in the sequence from high temperature to low temperature, the corresponding critical temperatures are 1060 ℃, 950 ℃ and 930 ℃respectively. The composition and morphology of the grain boundary phase are influenced by the collective effect of distortion degree of B2 grains and heat treatment. Coarse discontinuous α2 phase is easy to form at the boundaries of original B2 grains with high distortion degree, and is converted into α2+Orim structure if heat treated at B2+O phase region;The fine continuous O phase is inclined to form at the boundaries of dynamic recrystallized B2 grains with low distortion degree, which can be completely transformed into α2 if heat treated at B2+α2 phase region;no phase is formed at the boundaries of static recrystallized B2 grains.Precipitates within B2 grains are mainly influenced by heat treatment. α2 and O can directly and independently precipitate from B2,O can also attach α2 to form an α2/Orim core-shell structure. The α2/Orim core-shell structure indicates α2 has good stability at low temperature. After solid solution and aging treated, mixed microstructure with bi-size precipitates emerge within B2 grains, which can be coarse α2/Orim+ fine O or coarse OI+OII with the corresponding solution treatment at B2+α2 and B2+O respectively. The size distribution of B2 precipitated phase in grain is the main factor affecting the mechanical properties. Larger size is favorable for the ductility and toughness of alloy, but unfavorable for strength and creep resistance.
作者
周毅
曹京霞
黄旭
谭启明
隋楠
张明达
ZHOU Yi;CAO Jingxia;HUANG Xu;TAN Qiming;SUI Nan;ZHANG Mingda(AECC Beijing Institute of Aeronautical Materials,Beijing 100095,China;AECC Key Laboratory of Advanced Titanium Alloys,Beijing 100095,China)
出处
《航空材料学报》
EI
CAS
CSCD
北大核心
2020年第4期25-35,共11页
Journal of Aeronautical Materials
基金
航空动力基金(6141B090329)。
