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高铝钛铸造镍基高温合金有比重小、高温强度高、综合性能好的特点.合金中有γ固溶体、Ni_3(Al,Ti)、TiC、M_(23)C_6等主要相,成分出格或工艺控制不当时,可能出现σ、μ等相.调整合金元素的种类和数量,对合金的相组织有决定性的作用,影响持久强度等性能和σ相的析出,其中以铬、铝、钛最为关键.如γ′强化相大量析出后,基体中富集易形成σ相的铬、钼、钴等元素,给σ相的形成创造条件.合金中铝钛总量愈高,γ′相愈多,γ基体中铬含量逐渐增多,将促进σ相析出.如铝铬量一定,随着钛的增多,基体中铬、钼和钴趋向增加,也促使σ相析出.铝钛增多,钛的树枝状偏析严重,能引起(γ+γ′)共晶增多,σ相往往在时效过程中于(γ+γ′)共晶周围析出.经变化合金中铝、钛、铬的含量,研究其持久强度和瞬时性能等的影响,得出一般情况下可用9Cr系,铝钛总量可在10.2至11.4%之间,其900℃,32公斤/毫米~2下的持久时间超过100小时,瞬时性能良好.只要铝保持5.5%,则钛可由4%至5.5%.其它如钼、碳、硼、钴、钒等均分别予以研究讨论.防止析出σ相,除控制铬、铝、钛等的含量外,还必须注意铸造工艺,密切注意铸温和造型技术,减少偏析.
High-aluminum titanium cast nickel-base superalloy has the characteristics of small specific gravity, high temperature strength and good comprehensive properties. The alloy has γ solid solution, Ni_3 (Al, Ti), TiC and M_ (23) C_6, When the control is improper, the phases of σ, μ, etc. may occur.Adjusting the types and amount of the alloying elements has a decisive effect on the phase structure of the alloy, influencing the properties such as long-lasting strength and the precipitation of the σ phase, of which chromium, aluminum and titanium are the most important As the γ ’strengthening phase is precipitated in a large amount, elements such as chromium, molybdenum and cobalt which are easy to form σ phase are enriched in the matrix, which will create conditions for the formation of σ phase. As the content of chromium increases, the content of chromium increases gradually, which will promote the precipitation of σ phase.As certain amount of aluminum and chromium, with the increase of titanium, the content of chromium, molybdenum and cobalt tend to increase and also precipitate the σ phase. The segregation is serious and the (γ + γ ’) eutectic phase increases. The σ phase tends to precipitate around the (γ + γ’) eutectic during the aging process. The change of aluminum, titanium, And instantaneous performance and other effects, come to the general availability of 9Cr Department, the total amount of aluminum Titanium can be between 10.2 to 11.4% of its 900 ℃, 32 kg / mm 2 lasting more than 100 hours, the instantaneous performance is good. As long as the aluminum to maintain 5.5%, the titanium from 4% to 5.5%. Other such as molybdenum, carbon, boron, cobalt, vanadium and so were Research and discussion to prevent the precipitation of σ phase, in addition to control the chromium, aluminum, titanium and other content, but also must pay attention to the casting process, pay close attention to casting mild modeling techniques to reduce segregation.