TWO KINDS OF VARIANT IN SHAPE MEMORY MATERIAL

In shape memory materials,that have been trained to have a two way shape memory effect(TWSM),themartensitic variants are classified into two groups,i.e.,preferentially oriented variants and self-accommodatingvariants.Applied stress may promote or constrain the transition of preferentially oriented variants and so changetransformation temperatures but has no essential effect on self-accommodating variants.According to the pointof view mentioned above,some experimental phenomena during thermocycling of a TWSM device may be ex-plained,such as the absence of synchronization between the plot of resistance change.temperature and the plotof memory strain vs.temperature.     

Microstructure Evolution of Intermetallics Produced by Laser Powder Deposition

NiAl intermetallic alloys are potential high temperaturestructural materials in aeronautical and astronauticalindustries[1].However,the poor ductility andtoughness at room temperature severely restrict theirengineering applications[2,3].It is important todevelop new technology to product intermetallicmaterials for the improvement of the comprehensiveproperties and the workability.Laser powder depositionhas been used to synthesize many new materials.Furthermore,if incorporated with rapid proto…     

Ni-Cr-Fe-Si-B合金涂层及铝青铜基体熔合区组织的研究

采用钨极氩弧焊方法在铝青铜基体上施焊了Ni—Cr-Fe-Si—B合金涂层，并运用金相显微镜、扫描电子显微镜及能谱分析了喷涂层、熔合区及热影响区的组织形貌和成分分布。结果表明，喷焊时，在涂层与基体界面两侧各组元均发生了明显的扩散，Cu、Ni组元间可相互取代，基体融合区组织的基本组成仍为α (α γ2)，但同时也形成了Cu2FeAl7、NiAl3等新相，且融合区组织细小，涂层与基体间为冶金态结合。     

钨钴硬质合金电化学蚀刻加工研究

对YG6硬质合金电化学蚀刻工艺进行了研究,提出了采用光致抗蚀剂作保护膜,在生成一定钝化膜的情况下进行电化学蚀刻的方法.在一定的蚀刻深度范围内,该工艺的可控性好、腐蚀区表面质量较好.     

Formation and thermal stability of amorphous Ni-Mo-P alloys

The experimental researches on the chemical deposition of Ni-Mo-P amorphous alloys were carried out by adding Na2 MoO4 into acidic solutions. The optimum technology conditions were obtained by orthogonal design experiments. The structures and the relationship between compositions and their thermal stability were studied by energy spectrum (EC), scanning electron micrograph and X-ray diffraction spectrum. Compared with Ni-P amorphous alloys, the Ni-Mo-P amorphous alloys have high crystallization temperature and thermal stability, and the hardness reaches its peak when the annealing temperature is 500 ℃. With the increase of the heat treatment temperature, the surface morphology of the alloys changes.     

低碳低合金铸钢力学性能的研究

利用Olympus光学显微镜、扫描电镜(SEM)及能谱分析(EDAX)探讨了等温淬火工艺对低碳低合金CrMnSi铸钢力学性能的影响,并通过XRD定量分析了相的组成.结果表明,合适的等温淬火工艺,可获得一定数量的贝氏体和残余奥氏体(约6%)的复合组织,冲击断口形貌由解理刻面变为韧窝状,铸造成形无缺口试样(10 mm×10 mm×55 mm)的冲击韧度由ακ≤30 J/cm2增加至ακ≥170 J/cm2,硬度HRC≥40,具有较高硬度和冲击韧度的配合.     

Influence of electroplating conditions on magnetic properties of Fe-36wt.% Ni alloy film

A Fe-Ni soft magnetic film was prepared in sulphate solution by electroplating. The influences of the molar ratio of n [Fe2+ ]/ n [Ni2+ ], current density, bath temperature, pH and L-ascorbic acid concentration on magnetic properties of Fe-Ni alloy film were investigated. The results show that the saturated flux density(BS) of the film increases initially and decreases after it reaches the specific value with the increase of n [Fe2+ ]/ n [Ni2+ ] molar ratio, current density, bath temperature and pH. However, the relationship between L-ascorbic acid concentration and B S keeps linear. It is observed that the coercive force( Hc) is enhanced with the increase of n [Fe2+ ]/ n [Ni2+ ] molar ratio, current density and pH. By comparison, when the bath temperature increases, Hc always decreases. With the increase of L-ascorbic acid concentration, the coercive force increases initially and then decreases.     

Effect of grain size on high-temperature oxidation behavior of Cu-80Ni alloy

1　INTRODUCTIONTheoxidationofunalloyedcopperandnickelhasalreadybeenstudiedindetail.Whilethehigh tem peratureoxidationofCu Nialloys ,alsostudiedanumberoftimestodate[13] ,isanexampleofarela tivelysimpleclassofscalingofbinaryalloysbyasin gleoxidant,becausethemetalsformacontinuousse riesofsolidsolutions ,whiletheiroxides ,CuO ,Cu2 OandNiO ,exhibitsmallmutualsolubilitiesandshowsignificantdifferencesinthethermodynamicstabilityandparabolicgrowthrates .Thus ,copper richalloysformexternalscales…     

含共晶碳化物Fe－Cr－Mn合金在高温含硫气氛中的腐蚀研究

对含碳量为０．５０－２．６３％的Ｆｃ－Ｃｒ－Ｍｎ合金在８００℃下含硫混合气氛中进行腐蚀试验．用Ｘ射线物相分析法分析了腐蚀产物种类及其相对含量，现实测定了元素在腐蚀产物中的分布及试样亚表层共晶碳化物的腐蚀行为。结果表明：试验合金比高Ｎｉ耐热钢具有高的抗腐蚀性；合金的腐蚀行为受硫化及氧化腐蚀双重制约，因而使合金的腐蚀增重呈现峰值，随气氛氧化性增强，峰值向低碳方向移动；共晶碳化物具有比金属基体略好的抗腐蚀性。     

High temperature corrosion mechanisms and effect of alloying elements for materials used in waste incineration environment

Corrosion products on two typical materials, SA213-T12 steel and alloy 625 exposed to the actual combustion gas, were analyzed in addition to laboratory tests for penetration of corrosive matter. It has been clarified that corrosion products of oxides containing a little chlorides and sulphides show lamellar structures and that at the alloy-scale interface, chlorination, sulphidation, and oxidation occur under a low P_O2-high P_Cl2 condition. The formation of scale structures and the effect of corrosion-resistant alloying elements can be explained according to the stability tendencies of metals, chlorides, and oxides in the M-Cl-O equilibrium diagrams. The severity of corrosion environments at the interface is influenced by the penetration extent of corrosive matters through deposits and scales, and the protective effects of oxide films derived from alloying elements play an important role in preventing the corrosion. On the other hand, it has been shown that thermal fluctuation characterized in this kind of environment makes the lamellar scale structures and sometimes breaks and peels off the scale, and thus accelerates the corrosion. On the basis of the above mentioned knowledge, a new corrosion model is presented.