高速电弧喷涂Fe3Al／WC复合涂层高中蚀行为研究

采用自行研制的新型热喷涂Ｆｅ３Ａｌ／ＷＣ复合合金粉芯丝材,成功地用高速电弧喷技术制备出了Ｆｅ３Ａｌ金属化合物基金属陶瓷复合涂层。对涂民分、显微组织、涂层相结构和组成进行了分析。结果表明,涂层由以Ｆｅ－２６Ａｌ为主的Ｆｅ３Ａｌ基体相与约２０％的ＷＣ、Ｗ２Ｃ和α－Ａｌ２Ｏ３组成。对比研究了Ｆｅ３Ａｌ／ＷＣ涂层和电站锅炉钢２０ｇ从室温至６５０℃氧化环境条件下不同攻角的高温冲蚀磨损性能,结果表明Ｆｅ３Ａｌ     

Al—Si系合金制备工艺与微观组织的关系

分别采用双级雾化、超音气体雾化、喷射沉积和金属型铸造等工艺制备了Ａｌ－２０Ｓｉ和２０２４－２０Ｓｉ－５Ｆｅ 合金。利用ＸＲＤ、ＴＥＭ 和ＳＥＭ 测试技术分析了制备工艺对合金相组成、α－Ａｌ相晶格常数和固溶度的影响。结果表明：当制备工艺的冷却速度达到１０３ Ｋ／ｓ 以上时,β－（Ｆｅ２Ｓｉ２Ａｌ９）、ＣｕＡｌ２ 和Ｍｇ２Ｓｉ相的析出得到有效抑制;第二相随制备工艺的冷却速度增大而细化,α－Ａｌ相的晶格常数减小;Ａｌ－２０Ｓｉ合金中硅元素在α－Ａｌ中的最大固溶度高达３．２０９％ 。     

GL渗铝钢管渗铝层的显微硬度及相组成

采用光镜、显微硬度计、扫描电镜（ＳＥＭ）、电子探针（ＥＰＭＡ）和Ｘ－射线衍射等试验方法，对感应料浆法（ＧＬ）渗铝钢管Ｆｅ—Ａｌ合金渗层的显微硬度和相组成特征进行研究。结果表明，ＧＬ渗铝钢管渗铝层显微硬度由表及里为６００～３２０ＨＭ，渗铝层由α─Ｆｅ（Ａｌ）固溶体、Ｆｅ３Ａｌ和ＦｅＡｌ相构成，不存在含铝较高的ＦｅＡｌ２、Ｆｅ２Ａｌ５和ＦｅＡｌ３等脆性相，改善了渗铝钢的抗变形能力和焊接性能。     

快速凝固Al－8．32Fe－3．4Ce合金中弥散合金相的TEM测定

用常规电子显微术及ＥＤＡＸ能谱分析方法，对压制的快速凝固Ａｌ－８．３２Ｆｅ－３．４Ｃｅ合金热暴露过程中存在的弥散合金相进行了测定，确定出一种新相属于三角晶系，点阵常数为ａ＝１．ｎｍ，ｃ＝０．７ｎｍ（用六角点阵表示），ＥＤＡＸ能谱定量分析表明此相相组成约为Ａｌ_８Ｃｅ。     

快速凝固Al—8.3Fe—1.9V—2.1Si合金的相转变

借助扫描电子显微分析、Ｘ射线衍射技术、差热分析手段研究了快速凝固Ａｌ－８．３Ｆｅ－１．９Ｖ－２．１Ｓｉ合金的相组成及相转变温度。结果表明，合金中的相组成为αＡｌ＋Ａｌ１３（Ｆｅ，Ｖ）３Ｓｉ相；在６３８℃－６４５℃温度范围内，立方结构的Ａｌ１３（Ｆｅ，Ｖ）３Ｓｉ相向六方结构的Ａｌ３（Ｆｅ，Ｖ，Ｓｉ）相转变。钒添加至Ａｌ－Ｆｅ－Ｓｉ合金中，提高了快速凝固Ａｌ－８．３Ｆｅ－１．９Ｖ－２．１Ｓｉ合金粉末的     

快速凝固Al—20Si—5Fe合金的退火组织变化

利用ＸＲＤ、ＤＳＣ以及ＴＥＭ方法研究了快速凝固Ａｌ－２０Ｓｉ－５Ｆｅ合金退火态的微观组织、弥散相结构和相转变。结果表明,快凝Ａｌ－２０Ｓｉ－５Ｆｅ合金组织中存在两种弥散相,δ－Ａｌ４ＦｅＳｉ２和初生Ｓｉ相,退火温度低于３１０℃时,δ－Ａｌ４ＦｅＳｉ２相未明显粗化;当退火温度高于３１０℃时,亚稳相δ－Ａｌ４ＦｅＳｉ２转变成稳定相β－Ａｌ５ＦｅＳｉ,β－Ａｌ５ＦｅＳｉ相随退火温度的提高而明显粗化。高温     

含Mo的Ni_3Al－Fe基合金在900－1100℃空气中的氧化行为

研究了含Ｍｏ的Ｎｉ３Ａｌ－Ｆｅ基合金在９００－１１００℃空气中的等温氧化行为，利用光学显微镜、ＳＥＭ、ＥＰＭＡ、ＸＲＤ分析了氧化膜的形态和结构．研究表明，含Ｍｏ的Ｎｉ３Ａｌ－Ｆｅ基合金由γ和β相组成．对应于γ相的氧化膜由多相组成，合金元素Ｆｅ和Ｍｏ使得γ相的氧化速率增大，氧化膜的粘附性和内聚力下降，其氧化反应激活能为４２．７ｋＪ／ｍｏｌ，Ｆｅ穿过Ａｌ２Ｏ３氧化层的扩散为氧化反应的速率控制步骤．而β相中的Ｆｅ和Ｍｏ，对其抗氧化性无不利影响，氧化膜仅由Ａｌ２Ｏ３．     

静态自延高温合成法形成陶瓷涂层的研究

采用静态自蔓延高温合成法（ＳＨＳ法）,在钢件表面形成陶瓷涂层。涂层的相组成主要是Ａｌ２Ｏ３＋（α－Ｆ３）＋少量Ｆｅ３Ａｌ：涂层由两层组成,外层为近乎纯Ａｌ２Ｏ３陶瓷层,过渡层为（α－Ｆｅ）＋Ａｌ２Ｏ３金属－陶瓷层,两层组织皆为长轴近似垂直于钢件表面的柱状晶;涂层与基体结合牢固。     

快速凝固Al—8.32Fe—3.4Ce合金中弥散合金相的TEM测定

用常规电子显微术及ＥＤＡＸ能谱分析方法，对压制的快速凝固Ａｌ－８．３２Ｆｅ－３．４Ｃｅ合金热暴露过程中存在的弥散合金相进行了测定，确定出一种新相三角晶系，点阵常数为ａ＝１．４ｎｍ，ｃ＝０．７ｎｍ，ＥＤＡＸ能谱定量分析表明此相相组成约为Ａｌ８Ｃｅ。     

电弧及高速电弧喷涂FeCrAl涂层的微观性能研究

用相同的喷砂和喷涂工艺参数,分别在４５＾＃钢基体上制备了电弧喷涂与高速电弧喷涂ＦｅＣｒＡｌ涂层,用扫描电镜分析了它们的表面形貌,测试分析了两种涂层及各种基体在距涂层－基体界面不同距离上的显微硬度值,得到了电弧喷涂及高速电弧喷涂基体上的热影响区宽度,讨论了涂层的显微组织对其硬度的影响,并测试分析了涂层和基体的截面线波动系数。试验结果表明,高速电弧喷涂ＦｅＣｒＡｌ涂层比普通电弧喷涂ＦｅＣｒＡｌ涂人有更     

RHEOLOGY FEATURE OF SIMPLE METAL MELT

The rheology feature of Sb, Bi melt and alloys was studied using coaxial cylinder high-temperature viscometer. The results showed that the curve of torsion-rotational speed for Sb melt presents a linear relation in all measured temperature ranges, whereas for the Bi melt, the curve presents obvious non-Newtonian feature within the low temperature range and at relative high shear stress. The rheology feature of Sb80Bi20 and Sb20Bi80 alloy melts was well correlated with that of Sb and Bi, respectively. It is considered that the rheology behavior of Sb melt plays a crucial role in Sb80Bi20 alloy and that of Bi melt plays a crucial role in Sb20Bi80 alloy.     

Microstructures and Mechanical Properties of a Newly Developed Austenitic Heat Resistant Steel

The effect of heat treatment on the microstructures and mechanical properties of a newly developed austenitic heat resistant steel(named as T8 alloy) for ultra-supercritical applications have been studied. Results show that the main phases in the alloy after solution treatment are γ and primary MX. Subsequent aging treatment causes the precipitation of M_(23)C_6 carbides along the grain boundaries and a small number of nanoscale MX inside the grains. In addition, with increasing the aging temperature and time, the morphology of M_(23)C_6 carbides changes from semi-continuous chain to continuous network.Compared with a commercial HR3C alloy, T8 alloy has comparable tensile strength, but higher stress rupture strength. The dominant cracking mechanism of the alloy during tensile test at room temperature is transgranular, while at high temperature, intergranular cracking becomes the main cracking mode, which may be caused by the precipitation of continuous M_(23)C_6 carbides along the grain boundaries. Typical intergranular cracking is the dominant cracking mode of the alloy at all stress rupture tests.     

The 15th Global Foundry Sourcing Conference 2014held in Qingdao China

Organized by Suppliers China Co., Ltd and co-organized by the National Technical Committee 54 on Foundry of Standardization Administration of China, the 15th Global Foundry Sourcing Conference 2014 （hereinafter referred to as FSC 2014） was successfully held on Sep. 23rd in Grand Regency Hotel, Qingdao. More than 500 delegates from home and abroad attended this conference, including over 130 purchasers from 20 countries and 380 domestic and foreign suppliers.     

LASER CLADDED TiCN COATINGS ON THE SURFACE OF TITANIUM

Laser cladded coatings of TiCN were produced on the surface of titanium. To obtain the optimal techniques, several conditions were tested by varying the laser scanning rate. The choice of shielding gas was also studied. The cladded coatings were then evaluated from the surface mechanics point of view based on their microhardness. The microstructure of some interesting samples was investigated by optical micrographs (OM). The results showed that under the condition of fixed pulse frequency and pulse width, the laser scanning rate and the shielding gas are the main factors influencing the components of coatings. TiCN coatings were decompounded and oxidized during the cladding process in the condition of no shielding gas of N2. X-ray diffraction results indicated that the composite coatings composed of TiCN, TiC, Ti2N, and TiO2 were produced using appropriate techniques. The results indicated that the best condition in terms of the surface microhardness is obtained when the scanning rate is 1.5mm / s, the pulse frequency is 15Hz, the pulse width is 3.0ms, and N2 is chosen as the shielding gas. The microhardness of the composite coatings is about 1331kg · mm - 2, which is about 4 times that of the substrate. The optical micrographs indicated that the cladding zone is made up of TiCN, TiO2, and some interdendritic Ti, but the diffusion zone mainly consists of the dendrites phase, and the cladded depth is about 80m, which is more than 2 times that of the laser nitrided sample. There were no microcracks or air bubbles in the cladded sample, which was cladded using the above optimal techniques.     

Microstructure and Mechanical Properties of X80 Pipeline Steel Joints by Friction Stir Welding Under Various Cooling Conditions

X80 pipeline steel plates were friction stir welded(FSW) under air, water, liquid CO_2 + water, and liquid CO_2 cooling conditions, producing defect-free welds. The microstructural evolution and mechanical properties of these FSW joints were studied. Coarse granular bainite was observed in the nugget zone(NZ) under air cooling, and lath bainite and lath martensite increased signifi cantly as the cooling medium temperature reduced. In particular, under the liquid CO_2 cooling condition, a dual phase structure of lath martensite and fi ne ferrite appeared in the NZ. Compared to the case under air cooling, a strong shear texture was identifi ed in the NZs under other rapid cooling conditions, because the partial deformation at elevated temperature was retained through higher cooling rates. Under liquid CO_2 cooling, the highest transverse tensile strength and elongation of the joint reached 92% and 82% of those of the basal metal(BM), respectively, due to the weak tempering softening. A maximum impact energy of up to 93% of that of the BM was obtained in the NZ under liquid CO_2 cooling, which was attributed to the operation of the dual phase of lath martensite and fi ne ferrite.     

INDUSTRY NEWS

China Securities News reported on March 21, 2014： Guangdong Hongtu Wuhan Die Casting Co., Ltd. （Wuhan Hongtu）, a wholly owned subsidiary of Guangdong Hongtu Technology （Holdings） Co., Ltd., held a groundbreaking ceremony recently. With the registered capital of 50 million Yuan, Wuhan Hongtu has a total land area of 100,000 square meters and a plant construction area of 72,000 square meters. It is expected to have a production capacity of about 30,000 tonnes of aluminum castings annually after it is put into production.     

STUDY ON PROPERTIES OF PULSE ELECTRODEPOSITED RE-Ni-W-P-SiC COMPOSITE COATINGS

The effects of pulse frequency f and duty cycle r on the deposition rate, composition, morphology, and hardness of pulse electrodeposited RE （rare earth）-Ni-W-P-SiC composite coatings have been studied. The results indicate that pulse current can improve the deposition rate of RE-Ni-W-P-SiC composite coatings; W, P, and SiC contents in the coating decrease with the increase of pulse frequency and reach the lowest value at f = 33Hz, whereas the RE content in the composite coatings increases with the increase of pulse frequency. SiC content decreases with the increase of duty cycle, W content reaches the lowest value, and P content reaches the highest value at r = 0.4; pulse current and RE can lead to smaller size of the crystalline grains; however, the effects of different pulse frequency and duty cycle on the morphologies of RE-Ni-W-P-SiC composite coatings are not obvious. The hardness of RE-Ni-W-P-SiC composite coatings is the highest when the duty cycle is at 0.6 and 0.8 and pulse frequency is at 50Hz. At the same pulse frequency, the hardness of RE-Ni-W-P-SiC composite coatings at r= 0.8 is higher than that at r= 0.6.     

GROWTH MORPHOLOGIES OF A BINARY ALLOY WITH LOW ANISOTROPY IN DIRECTIONAL SOLIDIFICATION

Two new classes of growth morphologies, called doublons and seaweed, were simulated using a phase-field method. The evolution of doublon and seaweed morphologies was obtained in directional solidification. The influence of orientation and velocity on the growth morphology was investigated. It was indicated that doublons preferred growing with its crystallographic axis aligned with the heat flow direction. Seaweed, on the other hand, could be obtained by tilting the crystalline axis to 45°. Stable doublons could only exist in a range of velocity regime. Beyond this regime the patterns formed would be unstable. The simulation results agreed with the reported experimental results qualitatively.     

THERMODYNAMICS STUDY ON THE DECOMPOSITION OF CHROMITE WITH KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.