镍基含硼钎料钎焊IC-6合金接头近缝区硼化物研究

研究了采用镍基含硼钎料钎焊IC -6合金时 ,接头近缝区出现的硼化物相的形貌、成分及结构 ,结果表明主要存在两种成分的硼化物相 ,r(Ni) :r(Mo)分别近似为 1 :1和 1 :2 .硼化物取向有一定规律 .对接头近缝区与合金中硼化物的形貌、成分进行了对比 .

High cycle fatigue behavior of the second generation single crystal superalloy DD6

The second generation single crystal superalloy DD6 with 0.10%Hf and 0.34%Hf （in mass fraction） was subjected to high-cycle fatigue （HCF） loading at temperatures of 700 ℃ in ambient atmosphere. SEM was used to determine the initiation site and the failure mechanism. Evolution of the microstructure was investigated by TEM observation. The results show that fatigue limit of DD6 alloy with 0.34%Hf is a little smaller than that of the alloy with 0.10%Hf. The fatigue cracks initiated on the surface or near the surface of the specimens. The crack would propagate along { 111 } octahedral slip planes, rather than perpendicular to the loading axis of specimen. Typical fatigue striation formed in steady propagation of fatigue crack. The fracture mechanisms of the high cycle fatigue of DD6 alloys with 0.10%Hf and 0.34%Hf are quasi-cleavage fracture. Different types of dislocation structures were developed during high cycle fatigue deformation.

含硼镍基钎料钎焊IC-6合金接头显微组织分析

通过对Ni B钎料在 12 2 0℃保温不同时间钎焊IC 6合金接头显微组织的分析 ,研究了钎缝中γ +γ′组织及近缝区硼化物的形成和变化。结果表明 ,仅依靠母材中Al元素的扩散钎缝中也能形成γ +γ′组织 ,但存在大量晶界 ,对接头高温性能不利。近缝区出现两种类型的硼化物 ,其Ni和Mo原子比分别近似为 1∶ 1和 1∶ 2 ,形貌和分布随保温时间不同而变化。

Isothermal oxidation behavior of single crystal superalloy DD6

The isothermal oxidation behavior of the second generation single crystal superalloy DD6 was studied at 1050 ℃ and 1100 ℃ in ambient atmosphere.Morphology of oxides was examined by SEM and their composition was analyzed by XRD and EDS.The experimental results show that DD6 alloy obeys subparabolic rate law during oxidation of 100 h at 1050 ℃ and 1100 ℃.The oxide scale exposed at 1050 ℃ is made up of an outer NiO layer with a small amount of Al2O3 and an inner Al2O3 layer.The oxide scale exposed at 1100 ℃ is made up of an outer Al2O3 layer with a small amount of NiO,an intermediate layer,mainly composed of Cr2O3 and TaO2,and an inner Al2O3 layer.The γ＇-free layer was formed under the oxide scale at two temperatures.

IC-6高温合金的氧化性能与防护

测定了IC - 6高温合金在 90 0℃～ 110 0℃的氧化动力学曲线 .结果表明 :90 0℃ ,IC - 6合金的氧化膜主要由α-Al2 O3 、NiAl2 O4 和NiO构成并含有少量的NiMoO4 和MoO2 .10 5 0℃和 110 0℃氧化时 ,IC - 6合金表面生成了挥发性很强的MoO3 ,发生了氧化失重 .IC - 6合金上沉积NiCoCrAlY涂层后 ,90 0℃时 ,涂层的氧化膜主要为α-Al2 O3 ;10 5 0℃时 ,氧化膜主要为α -Al2 O3 和Cr2 O3 ,大大改善了合金的抗氧化性 .110 0℃时 ,氧化膜主要由α-Al2 O3 、NiAl2 O4 和NiO构成 ,涂层虽然有一定的保护性 ,但效果不如 90 0℃和 10 5 0℃时显著 .形成以α -Al2 O3 和Cr2 O3 为主的氧化膜是使合金沉积NiCoCrAlY涂层后抗氧化能力大大提高的直接原因 .

Thermodynamics analysis and precipitation behavior of fine carbide in K416B Ni-based superalloy with high W content during creep

The precipitation behavior of carbide in K416 B superalloy was investigated by means of creep measurement and microstructure observation. The results show that nanometer M6 C particles discontinuously precipitate in the γ matrix or along the γ/γ′ interface of the alloy during high temperature tensile creep. Thereinto, the amount of fine M6 C carbide increases as creep goes on, and the coherent interfaces of M6 C phase precipitating from the γ matrix are {100} and {111} planes. The thermodynamics analysis indicates that the solubility of element carbon in the matrix decreases when the alloy is deformed by the axial tensile stress during creep, so as to cause the carbon segregating in the regions of stress concentration and combining with carbide-forming elements M（W, Co）, which promotes the fine M6 C carbide to precipitate from the γ matrix.

IC-6合金TLP连接接头组织对高温拉伸性能的影响

研究了采用镍基含硼中间层合金在 1 2 2 0℃保温不同时间连接 IC- 6合金时 ,接头 90 0℃拉伸性能的变化。结果表明接头拉伸强度并未随扩散时间延长而不断提高。从断口分析可知 ,焊缝组织中的晶界强度和近缝区硼化物的形态、分布及数量决定了接头的拉伸强度和塑性。焊缝中的晶界强度高 ,裂纹沿晶界扩展至不利取向 ,转而沿近缝区硼化物扩展 ,断口上沿晶断裂所占区域少 ,对应接头强度较高 ,且具有一定的塑性。若晶界强度低 ,断口上主要表现为沿晶断裂 ,接头强度较低 ,且塑性差。在外应力作用下 ,硼化物发生脆性解理或由于与基体结合力低而脱开 ,其周围的包膜可以缓解硼化物上的应力集中 ,使裂纹扩展需要的应变能增加。

两种IC-6高温合金防护涂层的氧化行为

研究了IC - 6高温合金及其防护性涂层NiCrAlY和NiCoCrAlY涂层在 90 0～ 110 0℃时的氧化 .结果表明 :沉积NiCrAlY和NiCoCrAlY涂层后大大改善了IC - 6合金的抗氧化性 .在 10 0 0和 110 0℃时 ,NiCrAlY涂层的抗氧化性优于NiCoCrAlY涂层 .90 0℃时 ,NiCrAlY涂层氧化膜主要是α -Al2 O3 ,同时还含有少量的Cr2 O3 ;而NiCoCrAlY涂层氧化膜为单一的α-Al2 O3 ,但由于NiCoCrAlY涂层表面氧化膜不致密 ,降低了涂层的抗氧化性 .10 0 0℃氧化时 ,NiCrAlY涂层和NiCoCrAlY涂层的氧化膜主要由α -Al2 O3 和Cr2 O3

表面取向对IC-6合金高温氧化的影响

采用TGA、EDAX及XRD等研究了定向凝固IC-6合金表面取向对其等温、循环氧化行为的影响.发现平行于凝固方向的纵切样品在950℃及1050℃下经100小时的等温氧化速率均明显大于横切样品的.这与横切样品表面存在品界,有利于铝的短路扩散有关。相反,由于Al_2O_3膜比较容易剥落,使横切样品表面在950℃抗循环氧化能力比纵切样品的差。在1100℃,晶界短路扩散作用减弱,横切与纵切样品循环氧化行为都表现出灾难性失重现象。

Weldability and liquation cracking behavior of ZhS6U superalloy during electron-beam welding

The weldability of the ZhS6U nickel-based superalloy, which is prone to solidification cracking during electron-beam welding(EBW) repair processes, was investigated. The effects of two different pre-weld heat-treatment cycles on the final microstructure before and after welding were examined. Welds were made on flat coupons using an EBW machine, and the two heat-treatment cycles were designed to reduce γ′ liquation before welding. Microstructural features were also examined by optical and scanning electron microscopy. The results showed that the change in the morphology and size of the γ′ precipitates in the pre-weld heat-treatment cycles changed the ability of the superalloy to release the tensile stresses caused by the matrix phase cooling after EBW. The high hardness in the welded coupons subjected to the first heat-treatment cycle resulted in greater resistance to stress release by the base alloy, and the concentration of stress in the base metal caused liquation cracks in the heat-affected zone and solidification cracks in the weld area.

Research on Interlayer Alloys for Transient Liquid Phase Diffusion Bonding of Single Crystal Nickel Base Superalloy DD6

Transient Liquid Phase Diffusion bonding (TLP bonding) is an effective method to achieve excellent joint of DD6, which is a new generation single crystal superalloy to manufacture aero-engine turbine blades. In this paper, the interlayer alloys for DD6 TLP bonding were designed. The alloy foils with thickness 40 μm ~ 60 μm, width 4 mm were prepared by using a single roller rapid solidification apparatus and the TLP bonding of DD6 was conducted. Then the joint microstructure and alloying elements diffusion behaviors were analyzed. The results indicate that microstructures of interlayer alloys prepared are fine and homogeneous, the melting point range of alloys from 1070°C to 1074°C and their melting temperature interval is merely 20°C, when the chemical composition of alloys are 1.5 ~ 2.0Cr, 3.2 ~ 4.0W, 3.7 ~ 4.5Co, 2.2 ~ 3.0Al, 0.7 ~ 1.0Mo, 3.2B, remain Ni (wt%). When the welding parameters are bonding temperature 1200?C, holding time 8.0 hour and welding pressure 0.3 MPa, the compacted joints obtained and the microstructure of TLP bonding seams were similar to base metal. The bonding joint is composed of weld center zone, isothermal solidification zone and diffusion-affected zone. Within joint, the elements diffusion is sufficient and borides in the diffusion zone are fewer.

Ni_3Al(IC-6)合金防护涂层抗氧化性能研究

Ｎｉ３Ａｌ合金是一种新型高温合金，ＩＣ－６合金是不含Ｃｒ而含１４％Ｍｏ的Ｎｉ３Ａｌ合金。由于高温下Ｍｏ极易氧化升华，因此为使ＩＣ－６合金在高温下可靠工作，需选择ＮｉＣｒＡｌＸ涂层作为ＩＣ－６合金的保护涂层。采用磁控溅射技术，在专用装置上按通过系统研究提出的工艺涂覆ＮｉＣｒＡｌＸ涂层，并对其抗周期氧化性能进行了研究。试验表明：ＮｉＣｒＡｌＹＳｉ涂层对ＩＣ－６合金的防护是非常有效的。

IL-2、IL-6对地塞米松诱导小鼠胸腺细胞凋亡的调节作用

目的：以Ｄｅｘ诱导小鼠胸腺细胞凋亡为模型，研究细胞因子（ＩＬ２、ＩＬ６）对小鼠胸腺细胞凋亡的调节作用。方法：应用ＰＩ法检测亚二倍体细胞，二苯胺法测定胸腺细胞片段化ＤＮＡ含量（％），ＤＮＡ凝胶电泳，流式细胞计分析胸腺细胞表型、测定高钙细胞百分比。结果：发现地塞米松（Ｄｅｘ）与小鼠胸腺细胞共同培养引起细胞凋亡，胸腺细胞减少以ＣＤ４＋ＣＤ８＋细胞最明显。细胞凋亡具有时间效应并与Ｄｅｘ浓度有关。３～４ｗ小鼠胸腺细胞对Ｄｅｘ的敏感性高于６～８ｗ小鼠。高浓度（＞２００Ｕ／ｍｌ）ＩＬ２或１００Ｕ／ｍｌＩＬ２与ＩＬ６（１００Ｕ／ｍｌ）协同可减轻Ｄｅｘ诱导的胸腺细胞凋亡，其片段化ＤＮＡ和亚二倍体细胞明显减少，胞浆Ｃａ２＋浓度降低，胸腺细胞亚群分布得到纠正。单独应用ＩＬ６不能改变Ｄｅｘ诱导的胸腺细胞凋亡。结论：地塞米松可促进小鼠胸腺细胞凋亡，高浓度（＞２００Ｕ／ｍｌ）ＩＬ２或１００Ｕ／ｍｌＩＬ２与ＩＬ６（１００Ｕ／ｍｌ）协同可减轻Ｄｅｘ诱导的胸腺细胞凋亡。

6%Re/5%Ru单晶镍基合金的超高温蠕变行为和影响因素

通过对6%Re/5%Ru单晶镍基合金(质量分数)进行蠕变性能测试和组织观察,研究了合金的超高温蠕变行为和影响因素。结果表明:测定出合金在(1160℃,120 MPa)的蠕变寿命为206 h。中期稳态阶段,位错在基体中滑移和攀移越过γ′相是合金的变形特征,γ基体中溶解的难熔元素可增加位错在基体中运动的阻力。超高温蠕变期间,随温度提高γ′相发生溶解,可减小筏状γ′相的尺寸,提高位错攀移越过γ′相的速率,特别是当温度大于1170℃时,合金的施加温度敏感性使筏状γ′相的尺寸减小,应变速率提高,这是合金蠕变寿命大幅度降低的主要原因。蠕变后期,基体位错可在位错网破损处切入γ′相,其中,切入γ′相的位错可由{111}面交滑移至{100}面形成K−W锁,抑制位错的滑移和交滑移,可改善合金的蠕变抗力。而在颈缩区域较大的有效应力可开动位错的双取向滑移,致使筏状γ′相扭折,并在扭折区域发生裂纹的萌生和扩展,直至断裂,这是合金在超高温蠕变期间的变形和损伤机制。

Effect of long-term thermal exposure on microstructure and creep properties of DD5 single crystal superalloy

The effect of thermal exposure on the microstructure and creep properties of the Ni-based single crystal superalloy in different test conditions was studied.Long-term exposure was performed at 1,000 ℃ and 1,100 ℃ for 500 h prior to the creep tests.The creep lifetime is found to be improved after the long-term exposure at 1,000 ℃ for 500 h as a result of the formation of secondary M_(23)C_(6) in the interdendritic region.The coarsening of γ’ precipitates accompanied by the formation of TCP phase lead to the degradation of alloy,which is responsible for the reduction of the creep lifetime of Ni-base single crystal superalloy after long-term exposure at 1,100 ℃ for 500 h.The creep lifetime of 1,000 oC thermally exposed sample under the conditions of 1,093 ℃/137 MPa is lower than that of heat-treated state.Thermal exposure at 1,100 ℃ for 500 h causes the creep lifetime to drop drastically.

Thrust force model for ultrasonic-assisted micro drilling of DD6 superalloy

As a typical refractory material,the DD6 nickelbased single-crystal superalloy has important applications in the aviation industry.Ultrasonic-assisted drilling is an advanced machining method that significantly improves machining of refractory materials.The drilling thrust force influences the hole surface quality,burr height,and bit wear.Therefore,it is necessary to predict the thrust force during ultrasonic-assisted drilling.However,there are few reports on the modeling of the thrust force in the ultrasonicassisted drilling of micro-holes.A thrust force prediction model for ultrasonic-assisted micro-drilling is proposed in this study.Based on the basic cutting principle,the dynamic cutting speed,dynamic cutting thickness,and acoustic softening effect caused by ultrasonic vibrations are factored into this model.Through model calibration,the specific friction force and specific normal force coefficients were determined.The model was verified through ultrasonic-assisted drilling experiments conducted at different feed rates,spindle speeds,frequencies,and amplitudes.The maximum and minimum errors of the average thrust force were 10.5%and 2.3%,respectively.This model accurately predicts the thrust force based on the parameters used for ultrasonic-assisted micro-hole drilling and can assist in the analysis and modeling of DD6 superalloy processing.

Surface Recrystallization in Nickel Base Single Crystal Superalloy DD6

The samples of single crystal superalloy DD6 are grit blasted and then heat treated either with the standard heat treatment procedure or in the temperature range of 1 000-1 250 ℃ for 4-16 h at vacuum atmosphere, then the recrystallization behavior of DD6 alloy is investigated. The results show that the equiaxed recrystallization grains form in the 7 phase region where the as-cast γ＇ phases have been dissolved completely, and cellular recrystallization forms in the region where the ascast γ＇ phases have been dissolved partially. The cellular recrystallization area consists of cellular grains, and the cellular grain consists of cubic γ＇ phase, lamellar γ＇ phase and γ＋γ＇. The coexistence of the equiaxed recrystallization zones and cellular recrystallization zones is a re- crystallized characteristic of the cold worked single crystal samples which are heat treated at a temperature lower than the solu- tion temperature. When the heating temperature is higher than 1 150 ℃, with the increase of heat treating temperature, the equiaxed recrystallization zone expands, whereas the cellular recrystallization zone shrinks. All the deformed regions are consumed by equiaxed recrystallization after annealing at solution temperature.

定向凝固Ni_3Al－Mo基合金高温氧化研究

利用热天平连续称重，研究了Ｎｉ３Ａｌ－Ｍｏ基合金（ＩＣ－６）在１２７３，１３７３Ｋ的空气中恒温３００ｈ的氧化行为．用ＥＰＭＡ及ＸＲＤ分析了氧化层的结构和成分，；ＩＣ－６合金的氧化层中包括ＮｉＡｌ２Ｏ４，ＮｉＭｏＯ４，ＭｏＯ２相．氧向内扩散及ＭｏＯ２氧化形成挥发性ＭｏＯ３同时影响着ＩＣ－６合金的氧化进程，氧化反应方程式可表示为：理论方程与实验数据吻合较好．ＭｏＯ３在１２７３、１３７３Ｋ的挥发速率常数分别为３．２７×１０－５和２．５５×１０－４ｍｇ／ｃｍ２·ｓ．

TLP连接接头近缝区一种硼化物的TEM研究

利用透射电镜研究了采用镍基含硼中间层合金TLP连接IC 6合金时 ,接头近缝区出现的一种硼化物相的形貌、结构及生长机制 ,表明其化学式可用Mo2 NiB2 表示 ,具有体心正交结构 ,硼化物与周围基体之间存在确定的取向关系 ,(2 11) boride//(111) γ′,<111>boride//<12 3>γ′。