用EB-PVD技术制备Ni-Co-Cr基高温合金的组织和力学性能

采用电子束物理气相沉积（EB-PVD）技术制备出厚度为0．3mm的Ni-Co-Cr基高温合金薄板,并用X射线衍射仪、光学显微镜、扫描电镜和拉伸设备研究了该合金热处理前后的显微组织及力学性能。结果表明,制备态合金为微晶结构,缺陷相对较多;热处理后晶粒迅速长大,缺陷密度大幅下降,并在晶粒内部形成了主要的沉淀强化相γ’相。与制备态合金相比,热处理后合金的力学性能得到明显改善,说明EB-PVD技术可以为制备性能优良的高温合金薄板提供一条新途径。     

EB-PVD制备SOFC电解质涂层的显微结构表征

采用大功率EB-PVD工艺在NiO-YSZ多孔基体上制备了20μm厚的YSZ电解质涂层材料。SEM分析表明制备态涂层表面由1μm～10μm的晶粒组成并含有少量微米级的孔隙，涂层材料的断面SEM表明涂层致密并和基体结合良好。EPMA分析显示初始蒸发阶段制备的涂层材料内Y，O元素分布均匀，Zr元素的分布存在一个梯度。XRD分析表明：涂层为典型的立方相结构并表现出择优取向特征。     

EB-PVD热障涂层高温氧化过程中的显微结构和相分析

采用磁控溅射方法在镍基单晶高温合金基体上沉积NiCrAlY粘结层，电子束物理气相沉积方法（EB－PVD）沉积陶瓷层（7mass%Y2O3-ZrO2)。用X－射线衍射（XRD）、扫描电镜（SEM）等研究了EB－PVD热障涂层热循环过程中的相变，同时观察了样品的形貌变化。结果表明，EB－PVD方法沉积的陶瓷层，其柱状晶粒簇拥成团，表面比较致密，然而晶粒簇间存在间隙，允许柱状晶横向伸缩，使基体能在相对大的范围内自由膨胀。经高温氧化后，陶瓷层表面变得疏松，柱状晶粒簇间距增大，随着热循环的继续进行，相邻较大的间隙互相连接而形成微裂纹，并逐渐横向及纵向扩展，循环氧化比恒温氧化更易于产生显微裂纹。1050℃热循环过程中，ZrO2正方相的c/a轴比值逐渐增加，Y2O3含量逐渐减少，非平衡正方相逐渐分解成平衡正方相和立方相。循环300次后，观察到少量从平衡正方相转变而来的单斜相。     

EB-PVD梯度热障涂层的制备及其热疲劳性能

采用ＥＢ－ＰＶＤ的方法,连续蒸发按一一分比混合的Ａｌ＋Ａ１２Ｏ３＋ＺｒＯ２混合源,在Ｎｉ基高温合金基体上制备了一种新型结构的热障涂层,ＳＥＭ和ＥＤＳ的观察、分析表明,这作层实现了由金属粘结层向陶资顶层的微观结构的梯度过渡和化学成分的连续变化。涂层的基本结构为ＮｉＣｏＣｒＡ１Ｙ／Ｎｉ３Ａｌ＋Ａ１２Ｏ３／Ａ１２Ｏ３ＺｒＯ２／ＺｒＯ２。这北度热障涂层在１０５０℃的抗高温氧化性能优于传统的二层结构的热障涂     

EB-PVD制备SOFC电解质涂层的显微结构表征

采用大功率EB-PVD工艺在NiO-YSZ多孔基体上制备了20 μm厚的YSZ电解质涂层材料.SEM分析表明制备态涂层表面由1 μm～10 μm的晶粒组成并含有少量微米级的孔隙,涂层材料的断面SEM表明涂层致密并和基体结合良好.EPMA分析显示初始蒸发阶段制备的涂层材料内Y,O元素分布均匀,Zr元素的分布存在一个梯度.XRD分析表明:涂层为典型的立方相结构并表现出择优取向特征.     

EB-PVD制备Ni-20.3Cr-4.6Co-2.1Al薄板力学性能研究

对采用电子束物理气相沉积（EB-PVD）技术制备Ni-20．3Cr-4．6Co-2．1Al高温舍金薄板制备态的力学性能进行了研究。结果表明：制备态舍金薄板常温（25℃）拉伸和高温（800℃）拉伸强度，后者比前者明显降低，但伸长率显著提高。常温和高温拉伸宏观断口形貌呈现裂纹瞬断区和裂纹扩展区两个不同的断裂区域。断裂区域均呈现明显的韧窝特征，其形态、大小以及数量有所差别，断裂方式为微孔聚集型和穿晶断裂的混合型。微区平面残余应力表明，制备态舍金薄板基板面和沉积面残余应力均为拉应力，且沉积面的拉应力高于基板面。     

时效热处理对EB-PVD镍基合金薄板组织与力学性能的影响

采用电子束物理气相沉积方法(EB-PVD)成功制备了直径为1000 mm,厚度为0.10～0.13 mm的镍基合金薄板.利用光学显微镜(OM)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)等测试方法,对时效热处理前后试样形貌、析出相组成、高温拉伸性能进行了研究.结果表明,镍基合金薄板材料时效热处理后,晶粒长大,随时效时间延长,晶粒长大速率明显降低.在时效过程中,有细小碳化物颗粒在晶界析出,衍射花样分析表明,碳化物为FCC结构的(Cr,Fe)23C6.时效热处理后,镍基合金薄板材料高温拉伸性能有了很大提高,延伸率有一定的降低.     

EB-PVD工艺中的熔池飞溅对TBCs的影响

采用电子束物理气相沉积技术在高温合金基体表面制备了YSZ热障涂层试样来分析沉积过程中产生的熔池飞溅对涂层性能的影响。对试样进行高温循环氧化实验,采用SEM对不同状态下试样的显微结构进行分析。结果表明,沉积过程中飞溅影响区高于涂层表面,在沉积过程中一直对其边界区域形成遮挡,造成飞溅影响区边界处组织疏松,且该区域边界在热循环过程中容易产生裂纹,使涂层体系过早失效。     

热处理对Fe-36Ni因瓦合金箔热膨胀及力学性能的影响

研究了60 μm厚Fe-36Ni因瓦合金箔冷轧态、退火态及淬火态的热膨胀行为及力学性能演变规律和作用机理。结果表明,冷轧态合金具有最小的热膨胀系数,淬火态次之,退火态热膨胀系数最大;热处理可有效提高合金的居里温度T_c,从而增大使用温度范围,900 ℃保温1.5 h淬火试样具有最优的热膨胀性能($bar{α}$_{(20-100 ℃)}=1.02×10^-6 K^-1,T_c=276 ℃),自由取向晶粒的增加是导致合金热膨胀系数增大的原因。与冷轧态相比,热处理后合金发生完全再结晶,并产生退火孪晶伴随有晶粒尺寸的变化和∑3ⁿ晶界比例快速升高,其中800 ℃保温1.5 h淬火试样的晶粒最细小(6.6 μm),∑3ⁿ晶界占比最高,具有最高的屈服强度(267 MPa)和抗拉强度(414 MPa)。淬火处理试样的综合性能优于退火试样。相同热处理方式下,升高热处理温度,一方面降低热膨胀系数,提高居里温度;另一方面也降低了强度。     

EB-PVD制备NiCrCoAl薄板800℃热处理微观组织研究

对采用电子束物理气相沉积（EB-PVD）技术制备Ni基高温合金薄板800℃真空保温过程中微观组织结构与硬度进行了研究。结果表明：制备态NiCrCoAl合金组织为γ-Ni固溶体,组织均匀细化、无沉淀析出相、无位错,存在孪晶,晶粒中出现大量应变条纹：在热处理态800℃,5×10^-3Pa真空保温过程中,合金组织相结构未发生变化,合金的平面和截面组织呈现层片状结构,存在大量亚结构缺陷——孪晶、少量位错,在800℃保温16h,有少量碳化物沉淀析出物;随着合金保温时间的延长,应变条纹随之消除,沿（220）晶面的晶粒择优取向迅速长大。同时,显微硬度随之降低。     

Microstructure and mechanical properties of ODS Ni-based superalloy foil produced by EB-PVD

Y₂O₃ dispersion strengthened Ni-based superalloy foil 0.1 mm thick was deposited by EB-PVD technology and followed by hot isostatic pressing (HIP) treatment. The phase composition and microstructure investigations on as-deposited and HIPed superalloy foils were performed by XRD, SEM and TEM. Columnar crystals formed on the evaporation side and equiaxed grains formed on the substrate side. Cross-section observation showed 150–300 nm grains of matrix with 10–25 nm particles of Y₂O₃ homogeneously dispersed in them. After HIP treatment, columnar crystals broke and turned into equiaxed grains. Little growth of oxide dispersoids was observed. The results of room temperature tensile tests indicated that the tensile and plastic properties of the foil after HIP treatment are both promoted with the ultimate tensile strength and elongation percentage reached the values of 1230 MPa and 0.92 in contrast with 725 MPa and 0.49 that of the as-deposited foil, respectively.     

Evaluation of mechanical properties of a low-cobalt wrought superalloy

In the late 1970s and early 1980s, cobalt was subjected to significant supply and market pressures. Those pressures caused renewed attention to the use of cobalt in aircraft engines. A NASA-sponsored program called Conservation of Strategic Aerospace Materials (COSAM) was created in response to the supply problems with cobalt and other aerospace metals. Among the work performed in the COSAM program and simultaneously by others were several studies on laboratory-size heats of wrought nickel-base super-alloys. These studies suggested that the cobalt levels of the alloys might be reduced by about half, with minimal negative impact on mechanical properties. The Lewis Research Center procured a 1365-kg (3000-lb) heat of a modified Waspaloy having a reduced cobalt level. This article reports the results of a program performed at four gas turbine manufacturers which evaluated the mechanical properties of forgings fabricated from that heat. The alloy chemistry selected reduced the nominal cobalt level from 13.5 to 7.75 wt%. To compensate for the anticipated strength reduction caused by a slight reduction in the amount of γ, the nominal aluminum was increased from 1.3 to 1.5% and the titanium was increased from 3.0 to 3.2%. The increase in aluminum and titanium were intended to increase the amount of γ in the al-loy. Tensile, creep-rupture, low-cycle fatigue, and cyclic crack growth tests were performed. In addition the effect of hydrogen on the alloy was determined. It was concluded that, in the event of a cobalt short-age, a low-cobalt modification of Waspaloy alloy could be substituted for Waspaloy with little develop-ment in those applications that are not creep-rupture limited. With some additional development to better control the grain size, it is probable that most of the current Waspaloy requirements might be met with a lower cobalt alloy.     

Ru对镍基单晶高温合金高温持久性能的影响(英文)

在真空定向炉中浇注了具有[001]方向的不含Ru和含Ru两个单晶高温合金,其它合金元素的含量基本相同,研究Ru对单晶高温合金在(980℃,250 MPa),(1100℃,140 MPa)和(1120℃,140 MPa)条件下持久性能的影响。结果表明,加入Ru能提高单晶高温合金的高温持久性能,提高作用随着温度的升高而降低。在断裂后的两种合金试样中都观察到γ′相定向粗化和筏排化,并且在(1100℃,140 MPa)和(1120℃,140 MPa)条件试样中有针状的TCP相析出,而在(980 ℃,250 MPa)条件试样中无TCP相析出。加入Ru减少了TCP相的析出数量。最后,讨论了加入Ru带来的合金组织变化进而提高合金持久性能的原因。     

Effects of heat treatment on mechanical properties of ODS nickel-based superalloy sheets prepared by EB-PVD

A Y2O3 dispersion strengthened nickel-based superalloy sheet(0.15 mm thick) was prepared by electron beam physical vapor deposition(EB-PVD) technology.Different heat treatments were used to improve the mechanical properties of the alloy sheet.Differential thermal analysis(DTA) was used to examine the thermal stability of the as-deposited sheet.Element contents,phase composition and microstructure investigations on as-deposited and heat treated specimens were performed by X-ray fluorescence spectrometer(XRF),X-ray diffraction(XRD) and scanning electron microscopy(SEM).Tensile tests were conducted at room temperature on specimens as-deposited and heat treated.The results show that the as-deposited sheet is composed of equiaxed grains on the substrate side and columnar grains on the evaporation side.The as-deposited sheet shows poor ductility due to micropores between columnar grains.The strength and ductility can be improved effectively by annealing at 800°C for 3 h.For samples treated at 1100°C,the strength drops down due to the precipitates of Y3Al5O12(YAG).     

Mechanical properties of fine grained superalloy K4169 with addition of refiners

Grain refinement of superalloy K4169 was achieved by adding refiners into the alloy melt and their effects on the mechanical properties were investigated. The tensile properties at room temperature and 700℃ and low cycle fatigue properties at room temperature were compared for both conventional and fine grained test bars.The results indicate that the rupture strength, yield strength, elongation and reduction of area for refined grains are all much superior to those for coarse ones. Whereas the elongation and reduction of area of fine grained samples decrease at 700℃. Low cycle fatigue properties of samples with refined grains at room temperature are improved significantly. In addition, the degree of dispersion of low cycle fatigue data of samples with refined grains is diminished.     

Influence of thermal exposure on the microstructures and mechanical properties of a superalloy

The effects of long-term aging on microstructures and their influence on tensile and stress-rupture behavior of a corrosion resistant nickel-base superalloy are investigated. Samples are aged isothermally at 1073, 1123, or 1173 K for different times of up to 10,000 h and mechanical tests are performed on samples in both standard heat treatment (SHT) and aged conditions. Scanning electron microscopy (SEM) studies reveal that the coarsening kinetics of γ′ follows a linear law at different temperatures with the calculated activation energy, i.e., 255 kJ/mol, for γ′ growth according to Lifshitz-Slyozof-Wagner (LSW) theory. After long-term aging for more than 1 khours, σ phase appears in the alloy. The kinetics of σ formation can be described by the Johnson-Avrime-Mehl equation. Tensile experiments at room temperature and 1173 K and endurance experiments at 1173 K/274 MPa are performed to test the effect of σ phases on these properties and no remarkable harmful effect is found. γ′ coarsening can be used to explain the reduction of yield stress, which is tested by the Labusch-Schwarz hardening theory. Although the presence of the σ phase clearly does affect the fracture process, the σ phase does not embrittle the alloy.     

Effects of returns on composition,microstructure and mechanical properties of GH4169 superalloy

To recycle the returned alloy effectively, effects of returns proportion on alloy composition, microstructure and compression properties of superalloy GH4169 were studied by means of scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS) and thermal-mechanical simulator. The results show that returns addition has no significant effect on the main alloy elements content and the principle precipitates, but increases the volume fraction of Al_2O_3 inclusions, resulting in the increase of oxygen level of GH4169 alloy. Returns addition does not change the elastic and plastic deformation process at room temperature or at 1,150 °C, but high returns proportion GH4169 alloy shows improved compression strength and yield strength. The alloy with 100% returns shows a maximum compression strength 1,153.45 MPa at room temperature, while the alloy with 80% returns has a maximum value 69.3 MPa at 1,150 °C. Returns addition increases fluctuation range and reduces the stability of yield strength and compression strength of GH4169 alloy at room temperature. It is noted that the volume fraction and the size of Al_2O_3, and the fraction of Laves phase reach their maximum values in the GH4169 alloy with 60% returns, which exhibits maximum yield strength of 516.65 MPa at room temperature and 62.17 MPa at 1,150 °C.     

退火工艺对1100铝箔组织及性能的影响

采用显微硬度计、大型偏光显微镜、MTS力学性能试验机和BCS-30D通用板料成形性试验机等设备，研究了成品退火工艺对冷轧1100铝箔再结晶过程中显微组织、力学性能和成形性能的影响规律。结果表明，无中间退火工艺的冷轧1100铝箔的再结晶起始温度为220℃，终止温度为320℃，铝箔在成品退火温度为350℃时，获得稳定的最佳综合性能，σb≥110MPa，δa≥25％，n≥035，IE≥8mm，并据此对现场生产工艺进行了调整。同时对退火过程中的强韧化机理进行了探讨。     

Preparation and mechanical properties of Ni-Cr-Al alloy by EB-PVD

Ni-Cr-A1 alloy was deposited by electron beam-physical vapor deposition(EB-PVD) method. The microstructure was investigated on as-deposited and long-term aged alloy. The results indicate that grain on surface of asdeposited alloy is about 185 nm in size, and a laminated structure in cross-section is observed. However, after aging for 16 and 120 h at 760℃, the laminated structure is dissolved, and the individual grain can be seen clearly. Columnar crystals form on the evaporation side, and exquiaxed grains form on the substrate side. The major precipitate is γ‘ phase after prolonged aging at 760℃. Mechanical properties of the Ni-Cr-A1 alloy were also studied. The results show that the fracture of as-deposited alloy has mixed type at room temperature, and intergranular fracture among columnar crystals is observed. Compared to that of as-deposited alloy, fracture of alloy after aging for 16 and 120 h at 760℃ appears to involve ductile fracture with dimples.     

浇注温度对K417G合金组织及力学性能的影响

研究了不同浇注温度下的K417G合金试样。结果表明,1 450℃浇注,合金中碳化物以块状为主,γ′相边缘钝化,γ′尺寸为1μm左右;1 500℃浇注,合金中碳化物以长条形为主,γ′相边缘清晰,立方度较好,γ′尺寸为0.8μm左右。1 450℃浇注的合金屈服强度及断裂强度均高于1 500℃浇注的合金。合金拉伸裂纹主要产生于碳化物处,1 450℃浇注的合金,碳化物尺寸较小,产生裂纹需要的应力较大;1 500℃浇注的合金,碳化物细长,碳化物断裂所需应力较小。在760℃/645 MPa条件下,1 450℃浇注的合金,平均持久寿命可达到219 h,而1 500℃浇注的合金,平均持久寿命仅为25 h。前者的断裂方式为穿晶断裂,后者为沿枝晶断裂,断口上存在有部分疏松组织。