(1. 中國科學(xué)院 金屬研究所 高溫合金研究部，沈陽 110016；
2. 海軍駐哈爾濱氣輪機(jī)廠有限責(zé)任公司 軍事代表室，哈爾濱 150046)
摘 要: 總結(jié)中國科學(xué)院院金屬研究所高溫合金與金屬間化合物課題組近年來開展的幾種鑄造高溫合金中氮(N)的研究結(jié)果；討論了鑄造高溫合金中N的控制方法。結(jié)果表明：無論鎳基還是鈷基鑄造高溫合金，N含量隨Cr含量或返回次數(shù)和比例的增加而增大，過高的N含量降低合金的力學(xué)性能，并導(dǎo)致合金質(zhì)量明顯下降，但N的影響機(jī)理不同；對鎳基鑄造高溫合金，N主要以極難分解的TiN顆粒團(tuán)簇存在于合金熔體中，在凝固過程中作為核心促進(jìn)TiC碳化物的析出與快速長大，塊狀碳化物阻塞枝晶間的通道，降低合金液的流動性和補縮性，導(dǎo)致合金組織中的顯微疏松明顯增加以及合金力學(xué)性能的降低；對鈷基鑄造高溫合金，高N含量提高合金的初始凝固溫度，使得合金枝晶組織粗大，枝晶間板條狀M7C3共晶碳化物數(shù)量增多、尺寸增大，抑制周圍基體中M23C6相的沉淀，導(dǎo)致共晶碳化物/基體界面更容易形成裂紋而降低合金力學(xué)性能。
關(guān)鍵字: 鑄造高溫合金；鎳基高溫合金；鈷基高溫合金；氮；影響機(jī)理
（1. Department of Superalloys, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China;
2. Navy Commissary Department, Harbin Gas Turbine Co., Ltd., Harbin 150046, China）
Abstract:The resent work in the Department of Superalloys and Itermetallic Composites, Institute of Metal Research, about the effect of nitrogen (N) on the microstructure and properties of cast superalloys was summarized. The control of N cast superalloys melting process was discussed. The results show that N content increases with the increase of Cr content in the virgin alloys, and the increment of recycle times or revert proportion in reverted alloys. Increasing N content considerably reduces the mechanical properties of both cast Ni-based superalloys and Co-based superalloys. In cast Ni-based superalloys, N reacts mainly with Ti to form TiN particles in the melt, which acts as profuse nucleus for subsequent carbides nucleation and growth at a higher temperature than in the normal solidification. These blocky carbides with large size can block the dendrite channels, and reduce the fluidity of the final liquid fraction and the permeability of the solidification structure. Consequently, increasing N content results in a greater degree of microporosity, which leads to a significant decrease in the mechanical properties of cast Ni-based superalloys. In Co-based superalloy, high N content will extend the solidification window during the solidification process, and then leads to the coarse carbide eutectic structure by increasing the quantity of the interdendritic Cr7C3 carbide eutectic, which restrains the M23C6 particles precipitates in the interdendritic regions. This microstructure is conducive to promote the initiation and propagation of the cracks and decrease the mechanical properties of cast Ni-based superalloys.
Key words: cast superalloy; Ni-based superalloy; Co-based superalloy; nitrogen; effect mechanism
