K465高温合金铝化物涂层Ni/Al互扩散系数计算

根据铝化物涂层形成过程中Al原子浓度分布，采用有限差分法反求铝化物外层Ni／Al互扩散系数．结果表明：相同温度下，铝化物外层Ni／Al互扩散系数随Al原子浓度增加而增大，表现出与Al浓度相关性；合金表面渗铝外层Ni／Al互扩散系数明显小于纯Ni表面渗铝外层Ni／Al互扩散系数．     

CORRELATION BETWEEN OXIDATION BEHAVIOUR AND BORON CONTENT IN Ni_3Al

本文研究了含硼量为0-2.22at.-％的Ni_3Al在750-1150℃和3-100h条件下的氧化行为。结果表明,不同硼含量的Ni_3Al合金在不同温度下的氧化动力学曲线基本都符合抛物线规律。硼含量在0.52-1.37at。-％时抗氧化性能最好。研究了氧化膜的形态与结构。0-1.37at.-％B的Ni_3Al合金,表面形成以Al_2O_3为主的氧化膜,并含有少量NiO和NiAl_2O_4,含有2.22at.-％B的Ni_3Al合金,表面生成复杂的硼氧化物,破坏Al_2O_3膜的完整性,抗氧化性最差。但无硼合金中,NiAl_2O_4的含量最高,并在试样冷却过程中几乎全部剥离。     

EB-PVD热障涂层的弹性模量和断裂韧性研究

用压痕法测量EB-PVD热障涂层的弹性模量及断裂韧性。发现热障涂层的Vickers显微硬度和弹性模量随施压载荷增大而减小,当载荷为2.94N时,显微硬度和弹性模量接近稳态值,分别为6.3GPa和172GPa;断裂韧性平均值约为1.81MPa·m1/2。压痕法测得陶瓷层断裂韧性数据波动较大,其主要原因是陶瓷层显微结构不均匀,使压痕裂纹在涂层不同局部区域所遇到的扩展阻力不同。     

Morphological evolution of γ＇ phase in K465 superalloy during thermal fatigue

The alternative heating/cooling cycles （thermal fatigue ） of K465 superalloy were carried out. The specimens were held at 1 050 ℃ for 300 s, then quenched into 20℃ recycling water for 10 s as a cycle. During thermal fatigue, γ＇ precipitates changed typically from cubical to irregular shape aider 10 cycles, to complex configuration aider 20 cycles and raft-like shape aider 30 cycles. The very fine γ＇ particles precipitated inter the original γ＇ particles. The elastic energy dominated morphological evolution of large γ＇ precipitates, and the thermal stress induced the directional growth of precipitates that minimized the total energy of the system, and the nucleation theory controlled the formation of fine γ＇ precipitate. The results show that the volume fraction of γ＇ precipitates is increased with the increase of heating/cooling cycles, which improves the mechanical property of this alloy.     

TLP连接对一种镍基单晶高温合金拉伸性能的影响

采用Ni-Cr-B非晶中间层瞬间液相连接（Transient liquid phase bonding） 一种镍基单晶高温合金DD98，TLP连接在1230℃，8h真空条件下进行。利用扫描电镜进行微观组织观察和成分分析。在不同温度对接头与母材进行了拉伸实验。实验结果表明：接头的微观组织和化学成分与母材趋于一致；接头强度达到母材的标准，其它性能指标与母材相当，二者的应力一应变关系相同。     

Tensile and fracture behavior of DZ951 Ni-base superalloy

The tensile and fracture behavior of DZ951 directionally solidified Niobase superalloy was studied in the temperature range of 20-1 100 ℃. The fracture mode was examined by scanning electron microscopy. The results show the experimental temperature has no significant effect on the tensile strengths, which are greater than 1 000 MPa from room temperature to 800 ℃. The yield strength reaches its maximum （970 MPa） at 800 ℃. When the experimental temperature is higher than 800 ℃, the tensile and yield strengths decrease evidently and the ductility increases remarkably. The fractograph of fracture surface for the tensile specimen at room temperature shows a dimple-ductile fracture mode. The fractograph from 600 to 800 ℃ shows a slide fracture mode. The fractograph from 900 to 1 100 ℃ exhibits a creep rupture mode with uneven deformation.     

镍基单晶高温合金TLP连接

采用自制的镍茯合金柔性布作为中间层合金对DD98单晶高温合金进行瞬态液相（TLP）连接,TLP连接在1473-1523K,0.5-24H真空条件下进行。利用光学显微镜、扫描电镜对接头的微观结构和化学成分进行观察和分析,利用电子背散衍射测定了连接层和基体之间的结晶学取向。结果表明接头区域由连接区,中间金属／基体金属界面扩散区、基体金属区组成,均匀化处理后的接头与基体上的γ‘沉淀相的尺寸趋于一致,连接层与基体之间的取向匹配良好。     

钛含量对一种镍基单晶高温合金长期时效后的组织影响

研究了不同Ti含量对一种镍基单晶高温合金的铸态组织以及在1000℃长期时效后的组织演化.结果表明:随着Ti含量的增加,铸态组织中枝晶间区域面积以及枝晶间区域的γ/γ'共晶含量逐渐增加;长期时效后随着Ti含量的增加,筏形化程度越来越严重,逐渐有TCP相析出.     

Calculation Of Interdiffusion Coefficients Of Ni And Alatoms In Β--Nial Phase As Aluminide Coatings

通过纯Ni和K465合金表面渗Al涂层中Al原子浓度分布曲线的分析，考虑到K465合金复杂的化学成分和显微组织，基于一定的假设，推导出Wagner修正式，并分别计算了850，950和1050℃纯Ni和K465合金表面渗Al涂层中β-NiAl相Ni，Al互扩散系数。计算结果表明：K465合金表面渗Al层中β-NiAl相Ni，Al互扩散系数明显小于纯Ni表面渗Al涂层中β-NiAl相Ni，Al互扩散系数；与化学计量比β-NiAl相相似，K465合金表面渗Al中β-NiAl相Ni，Al互扩散系数与Al原子浓度有很大的相关性。简要分析了合金元素和析出相对渗Al涂层中β-NiAl相Al，Ni互扩散系数的影响。     

DZ40M合金高温低周疲劳性能及其断口分析

测定了定向凝固钴基高温合金ＤＺ４０Ｍ９０℃低周疲劳性能并观察了疲劳断口,结果表明,ＤＺ４０Ｍ合金具有较高的抗高温低周疲劳性能;疲劳裂纹起源于试样表面优先氧化的碳化物。基体中骨架状分布的碳化物阻滞裂纹扩展;氧化不仅促进疲劳劳裂纹的形成,而且加速了裂纹扩展。ＤＺ４０Ｍ合金的高温疲劳破坏机械疲劳与环境氧化双重和所致。