摘要
为了研究镍含量(5、15、25和35,at%)对Co-8.8Al-9.8W基高温合金时效组织演变及γ′强化相溶解行为的影响,运用SEM、XRD等对时效处理后合金的γ′相微观组织结构演变、γ′相相转变温度和显微硬度进行了研究。结果表明,Ni含量增加,γ′相溶解温度出现不同程度的提高,γ′相的体积分数也在逐渐增加。当Co-8.8Al-9.8W合金中Ni添加量为25%时,γ′强化相的溶解温度达到了1100℃。合金固相线温度和γ′相的形貌未发生明显变化。4种不同镍含量合金经900℃/50 h热处理后,基体均为典型的γ/γ′两相组织。经900℃/100 h热处理后,γ′相的体积分数出现不同程度的降低,且γ′相发生了明显的粗化。对4种合金900℃/50 h和900℃/100 h的显微硬度测量结果表明,当Ni含量由5%增加至15%时,其显微硬度升高;当Ni含量进一步增加时,合金的显微硬度却降低。合金的时效处理时间由50 h延长至100 h时,γ′相的体积分数减少并伴随着γ′相的粗化,导致Co-8.8Al-9.8W基合金的显微硬度降低。
To study the effects of nickel contents（5%, 15%, 25% and 35%, atomic fraction） on microstructural evolution and γ′ dissolution behavior of Co-Al-W base alloys, the γ′ phase microstructural evolution, γ′ phase transformation temperatures and microhardness of Co-Al-W base alloys with aging treatment were analyzed using scanning-electron microscope（SEM） and X-ray diffraction（XRD） etc. Results show that with the increasing of Ni content, γ′ solvus temperature increases at different degrees and the volume fraction of γ′ phase increases gradually. When the nickel content in Co-8.8Al-9.8W alloy reaches 25%, γ′ phase transformation temperature increases to 1100 ℃. The solidus temperatures and γ′ phase morphology of the four Co-Al-W base alloys are nearly unchanged. The typical γ/γ′ two-phase microstructure is generated in the four alloys after the heat treatment at 900 ℃ for 50 h. After aging at 900 ℃ for 100 h, the γ′ phase volume fraction decreases and the γ′ phase is obviously coarsened. The microhardness of the four alloys after heat treatment at 900 ℃ for 50 and 100 h indicates that the microhardness is raised from 5Ni alloy to 15 Ni alloy, but is lowered when further increasing the Ni content. With the aging treatment time from 50 h to 100 h, the volume fraction of γ′ phase decreases and γ＇ phase coarsens, which reduces the hardness of Co-8.8Al-9.8W-based alloy.
出处
《稀有金属材料与工程》
SCIE
EI
CAS
CSCD
北大核心
2017年第8期2288-2293,共6页
Rare Metal Materials and Engineering
基金
国家自然科学基金(51561019)
