将Al和Ti以外的FGH96高温合金所需的各种纯净原材料放在一个2 kg级的真空感应炉里进行熔化,用于制备母合金。母合金的O和N含量分别为45ppm和21ppm。然后在母合金中切出200 g左右的试块,放在Al2O3或MgO坩埚里,外边放一个石墨坩埚,防止合金液泄露。然后开始加热,用铂铑热电偶进行测温。从炉子底部通入氩气进行气氛保护,防止氧化和空气的渗入。以5K/min的速度加热到实验温度(1823K)。共设计了4炉实验(I-Ⅳ)。实验Ⅰ、Ⅱ和Ⅲ采用Al2O3坩埚,而实验Ⅳ采用MgO坩埚。坩埚尺寸为外径40mm、内径30mm、内部高度90mm。当温度达到1823K时,保持10分钟,使得合金液的温度和成分均匀、稳定。然后,分别在5、10、20和30分钟时采用内径6mm外径8mm的石英管进行取样,并进行水淬。为了保证取样位置一致,每次取样时先将石英管伸入合金液的底部,然后向上提起10mm,进行取样。在每个试样距离底部8mm的截面上观察夹杂物。先用400#砂纸进行粗磨,然后用800#、1200#和2000#砂纸逐级进行细磨,最后进行抛光。采用SEM-EDS分析金相试样表面裸露的夹杂物的成分、尺寸和形貌。进一步地,采用自动SEM (ZEISS, EVO18)-EDS (Oxford Instrument, INCA)设备定量分析夹杂物的数量、尺寸和成分。氧化物最小尺寸设置为0.5μm。最后,对在炉中冷却的4个合金锭进行化学成分检测。
All the pure raw materials required for FGH96 superalloy other than Al and Ti were melted in a 2 kg vacuum induction furnace for the preparation of the master alloy. The contents of O and N in the master alloy are 45ppm and 21ppm respectively. Then, cut out about 200 g of test blocks from the master alloy and place them in an Al2O3 or MgO crucible, with a graphite crucible placed outside to prevent the alloy liquid from leaking. Then start heating and measure the temperature with a platinum-rhodium thermocouple. Argon gas is introduced from the bottom of the furnace for atmosphere protection to prevent oxidation and the infiltration of air. Heat at a rate of 5K/min to the experimental temperature (1823K). A total of 4 furnace experiments (I- IV) were designed. Experiments I, II and III used Al2O3 crucibles, while Experiment IV used MgO crucibles. The crucible dimensions are an outer diameter of 40mm, an inner diameter of 30mm, and an internal height of 90mm. When the temperature reaches 1823K, maintain it for 10 minutes to ensure that the temperature and composition of the alloy liquid are uniform and stable. Then, samples were taken using quartz tubes with an inner diameter of 6mm and an outer diameter of 8mm at 5, 10, 20 and 30 minutes respectively, and water quenching was carried out. To ensure consistent sampling positions, each time a sample is taken, the quartz tube is first inserted into the bottom of the alloy liquid, and then lifted up by 10mm for sampling. Observe the inclusions on the cross-section of each sample at a distance of 8mm from the bottom. First, rough grinding is carried out with 400# sandpaper, then fine grinding is done step by step with 800#, 1200# and 2000# sandpapers, and finally polishing. The composition, size and morphology of the exposed inclusions on the surface of the metallographic specimens were analyzed by SEM-EDS. Furthermore, the quantity, size and composition of inclusions were quantitatively analyzed by using the automatic SEM (ZEISS, EVO18)-EDS (Oxford Instrument, INCA) equipment. The minimum size of the oxide is set to 0.5μm. Finally, the chemical composition of the four alloy ingots cooled in the furnace was tested.