摘要
利用XRD,SEM,TEM等实验方法,研究了铝热合成法制备的FeNiCrAl合金的微观组织,并研究了铝热剂成分中Al含量对合金拉伸性能的影响.结果表明,当铝热剂中Al含量不超过25.4%(质量分数)时,合金的主要组成相是奥氏体;当铝热剂中Al含量达到26.6%时,合金主要组成相为铁素体,同时析出颗粒状的NiAl相;随着Al含量继续增加,颗粒状析出相逐渐被编织状组织所取代.编织状组织的产生是液相调幅分解的结果.铝热剂中Al含量的增加,会降低合金的断后延伸率.当铝热剂中Al含量为26.6%时,合金的抗拉强度达到最大,为640.87MPa.
ABSTRACT The excellent thermal conductivity, low thermal expansion and high oxidation resistance of ferritic FeNiCrAI alloys, provide them with the potential to be replacements for nickel-based superalloys in high-tempera- ture applications. However, their usage is limited, because of their poor high-temperature mechanical properties. The high melting point of NiA1 intermetallic compounds, together with their excellent high temperature stability and similar lattice parameters to a-Fe, allow them to be used to coherently strengthen ferritic FeNiCrA1 alloys to extend their high-temperature performance. Traditionally, these Fe（Ni, Cr）/NiA1 alloys are prepared by vacuum re- action melting followed by an aging process. But the aging process has drawbacks including excessive cost, the length of aging time required and coarsening of the NiA1 phase at high temperature. A more cost-effective thermite reaction process, was tried to prepare the Fe（Ni, Cr）/NiA1 alloys. In this route, ferrite FeNiCrA1 alloys were strengthened by a high volume fraction nanoscale-NiA1 phase which was achieved without using the aging process. Several types of thermites were designed and studies were conducted to explore the transformationsof the alloy mi- crostructures and the changes of the tensile properties with the various thermite compositions. The microstructures of these thermites synthesized Fe（Ni, Cr）/NiA1 alloys were investigated using XRD, SEM, EDS, TEM and SAED.The effect of AI content in the thermites on the microstructures of the alloys was studied. Experimental results showed that when the thermites contained no more than 25.4% （mass fraction） orAl, the synthesized Fe（Ni, Cr）/Ni- A1 alloys were composed primarily of an anstenite phase. The main component phase of the alloy composites was transformed into ferrite when the mass fraction orAl in the thermites was 26.6%, meanwhile the NiAI particle pre- cipitates arose. As the A1 content of the mixture was further increased, the NiA1 precipitates were gradually re-
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2015年第4期483-491,共9页
Acta Metallurgica Sinica
基金
国家自然科学基金资助项目51472015~~
关键词
铝热反应
NI
Al
拉伸性能
液相调幅分解
thermite process, NiA1, tensile property, liquid spinodal decomposition
