HastelloyC－4型铸造镍基合金的组织及其腐蚀行为研究（上）

采用金相显微镜、Ｘ射线衍射和电于探针等显微分析手段和多种腐蚀试验方法，研究了ＨａｓｔｅｌｌｏｙＣ－４型铸造镍基合金的组织及其均匀腐蚀、晶间腐蚀与点蚀行为。试验结果表明，低的含碳量与含铁量和适量的镍、铬、钼的复合作用，使该合金对混酸介质具有良好的耐蚀性和较高的抗晶间腐蚀与抗点蚀性能。     

EFFECT OF SULPHURIZING-OXIDIZING ENVIRONMENT ON CREEP CRACK GROWTH OF Ni-BASE SUPERALLOY GH30

An investigation was made on the creep crack growth behaviour under static load at 1023 Kfor Ni-base superalloy GH30 exposed to air and air+10% SO_2.The results showed that inthe region of low stress intensity factor,the creep crack growth rate is higher in air+10%SO_2 than in air only,while in the high region,it is reverse.The fractograph of specimens hasbeen analyzed,and the mechanism of creep crack growth together with the influences of sul-phur and oxygen has been discussed as well.     

镍基非晶态合金材料真空钎焊特性研究

研究了非晶态Ｎｉ（８０－ｘ）Ｃｒ１０Ｂ２．５Ｓｉ４,５Ｆｅ３Ｃｕｘ合金钎料真空钎焊１Ｃｒ１８Ｎｉ９Ｔｉ的钎焊特性,并对铜的影响进行了探讨。结果表明,非晶态合金钎料钎焊性能优于晶态合金钎料,铜的适量添加有利于提高钎焊接头的综合性能。     

高Cr镍基单晶合金1050℃的高温氧化性能

采用X射线衍射(XRD)、扫描电镜(SEM)及能谱(EDAX)等手段,研究了一种高Cr镍基单晶高温合金在1050℃的高温氧化行为.结果表明,氧化初期合金增重迅速,氧化增重不遵循抛物线规律,表面氧化膜出现剥落,氧化过程由形成Al2O3和Cr2O3所控制.高温氧化期间,合金发生明显的外氧化和内氧化,外氧化膜Cr2O3和(Ni,Co)Cr2O4组成,内氧化物为Al2O3.在内氧化物上方出现贫Al富Ta区,元素贫化区尺寸随时间的延长而增大,富Ta相抑制基体中Al向外扩散,并抑制氧化膜生长.     

定向凝固合金DZ17G的高温低周疲劳性能研究

研究了定向凝固镍基高温合金ＤＡ１７Ｇ在８００℃下的低周疲劳性能,得到其循环应力－应弯曲线和应变－寿命曲线,并用最小二乘法回归至Ｍａｎｓｏｎ－ｏｆｆｉｎ方程的数学表达式;对疲劳断口进行了宏观及微观分析,发现裂纹主要在试样内部及近表面缺陷外萌生,裂纹一旦形成即穿晶扩展,且扩展方向垂直于加载轴。     

镍基高温合金的真空感应熔炼脱氧

研究了在真空感应炉中使用Cao坩埚熔炼镍基高温合金的脱氧效果，分析了加入0．02％C、0．5％Al对脱氧的影响。结果表明：采用CaO坩埚，选择合适的熔炼工艺及C、Al加入量，可使氧的含量降低到小于0.0006％。     

高铬镍基合金熔融硫酸盐热腐蚀过程中内氧化和内硫化行为的研究

通过对镍基合金进行不同温度的恒温熔融硫酸盐热腐蚀试验,对腐蚀产物横断面进行形貌观察及微区成分分析,研究了一种高铬镍基合金在恒温热腐蚀期间腐蚀产物分布特征及内氧化、内硫化行为。结果表明,该高铬镍基合金在900和950℃腐蚀100 h期间,合金氧化和硫化同时发生,且腐蚀产物中出现分层结构,由表及里各层中的主要氧化物分别为:Al2O3和Cr2O3,Al2O3,CrS。该合金在各温度的恒温热腐蚀期间,均发生Al元素的内氧化和Cr元素的内硫化;与外氧化膜相邻的区域为Al元素的内氧化区,远离外氧化膜的基体内部形成Cr元素的内硫化区;随腐蚀温度升高,内氧化区和内硫化区深度增加,内氧化物和内硫化物的尺寸增大。     

Estimating fatigue sensitivity to polycrystalline Ni-base superalloy microstructures using a computational approach

A computational study is conducted to determine the influence of microstructure attributes and properties on driving forces for fatigue crack formation and microstructurally small crack growth in a polycrystalline Ni‐base superalloy, IN100, a turbine disk alloy. A principal objective is to obtain quantitative estimates of the effect of variability of microstructure features on scatter in fatigue life or fatigue strength for a given life. Understanding is sought regarding sensitivity of driving forces to various microstructure attributes that may guide selection of the process route to tailor microstructure to achieve fatigue resistance. A microstructure‐sensitive crystal plasticity model is used to explicitly model individual grains and polycrystals, which is then used to explore effects of: (a) grain size distribution and (b) secondary and tertiary coherent γ′ precipitate size distributions and volume fractions on the cyclic inelastic strain distribution. Multiple statistical volume elements (SVEs) are subjected to random periodic boundary conditions to build up statistically significant measures of distributions of cyclic microplasticity. Multiaxial fatigue criteria with critical plane approaches are used to estimate the crack initiation life. Methods are developed for assessing crack formation and microstructurally small crack growth as a function of microstructure attributes.     

Interfacial fatigue crack propagation in Ni-base superalloy protective coatings

It is important to control the interface strength of coatings and composite materials; a feature that has been noted for many years. However, how can interface strength be evaluated and controlled? In order to explore this aspect, subcritical fatigue crack growth behaviour was investigated along the interface of a CoNiCrAlY coated Ni‐Base superalloy. According to the traditional fatigue test methodology, fatigue crack propagation tests were carried out, using double cantilever beam specimens. The resistance to the fatigue crack propagation was successfully evaluated by a fracture mechanics approach. Particular attention was given to the effects of surface finish of the substrate as a coating parameter, the test temperature, and long‐term thermal ageing after the coating.     

NiCrWSi系耐磨堆焊合金的设计和熔敷层性能研究

建立了堆焊合金定量设计的数学模型,有计划地设计熔敷层强化机构,创制了具有优良综合性能的ＮｉＣｒＷＳｉ系耐磨堆焊合金。测试了堆焊层的常温粘着磨损、高温（６００℃）粘着磨损和磨粒磨损性能,并分析了熔敷层硬度随温度的变化关系。