加Ag对（Bi,Pb）2Sr2Ca2Cu3Oy超导带材组织和性能的影响

研究了超导粉末中添加银对Ｂｉ系高温超导带材组织和性能的影响。添加银粉后，增大了银／氧化物之间的接触面积，改善了晶粒弱连接，相应地提高了Ｊｃ。另外加银粉可有效降低裂纹危害，增强带材的抗弯性能。     

碳含量对GH4199合金拉伸、持久性能及组织的影响

研究了碳含量对镍基变形高温合金GH4199拉伸、持久性能及显微组织的影响,并对碳含量变化所引起的组织及性能改变的原因进行了分析.结果表明:增加碳含量会阻止晶粒度长大,并明显改变碳化物的数量、形状及分布,碳化物类型主要以(W, Mo)6C为主,800℃长期时效500h后有M23C6析出,较低的碳含量对合金的拉伸及持久性能是有利的.     

Effects of solution treatment temperatures on microstructure,tensile and fracture properties of Co-free 18 Ni maraging steel

The study presents the influences of solution treatment temperatures (S.T.T.) on microstructure, tensile and fracture properties of 18 Ni cobalt free maraging steel. The results are thoroughly discussed in light of the prevailing microstructural conditions as revealed by optical and transmission electron microscopy, and detailed scanning electron fractography. It is found that tensile strength in both unaged and aged conditions is independent of solutioning temperature and, consequently, grain size. However, the tensile ductility, CVN and K_IC in aged condition get severely affected with the increase in S.T.T. because of a change occurring in the martensitic lath morphology from blocky to stringer type. This transition in the martensitic morphology starts at the prior austenitic grain size of 35-40 μm and is completed at 120-130μm. Solutioning at 1323 K followed by air cooling, however, results in thermal embrittlement of the steel due to grain boundary precipitation of TiCN. The prior austenitic grain size in this reaction plays only an indirect role. Based on these results, it has been suggested that the existing controversies on the effect of S.T.T. grain size on tensile ductility and fracture behaviour of maraging steels can be rationalized if the changes in martensitic lath morphology are considered as an important variable.     

Re含量对单晶高温合金组织和拉伸性能的影响

为优化一种单晶高温合金中的Re含量,在真空定向凝固炉中制备了3%Re和5%Re的镍基单晶高温合金,热处理后分别在980 ℃长期时效400、800、2 000 h,测试合金热处理后1 100 ℃拉伸性能,采用JMatPro软件计算了合金相图,通过光学显微镜、扫描电镜和能谱仪研究Re含量对合金枝晶组织,热处理组织和980 ℃时效400、800、2 000 h的组织和1 100 ℃拉伸性能的影响。结果表明,随着单晶高温合金中Re含量增加,一次枝晶间距轻微减小,共晶的体积分数升高;γ′相尺寸下降,立方化程度增加;不同Re含量合金时效800 h后无TCP相析出,时效2 000 h后有TCP相析出,随着Re含量增加,TCP相析出量增加。合金组织稳定性随着Re含量增加而降低。随着Re含量增加,合金的高温拉伸性能显著提高。      

混合稀土元素对HRB400钢组织及拉伸性能的影响

借助光学显微镜、扫描电镜以及电子万能试验机等手段研究了混合稀土含量对HRB400钢微观组织及力学性能的影响。结果表明,稀土含量的添加导致HRB400钢的上、下屈服点升高。并且随着稀土元素含量的增加,珠光体体积分数增多,片层间距减少,进一步提升了其抗拉强度;但是,0.045RE-HRB400钢中韧窝的数量及深度降低,使其延伸率以及断面收缩率均有所下降。      

Effects of copper and zirconium contents on microstructure and magnetic properties of Sm(Co,Fe,Cu,Zr)_z magnets with high iron content

The evolution of the microstructure,microchemistry and magnetic properties of the Sm(Co_(bal)Fe_(0.28)-Cu_yZr_x)_(7.6) magnets with different Zr and Cu contents was investigated.It is found that the coercivity of the Sm(Co,Fe,Cu,Zr)_z magnets is sensitive to Zr content.The deficiency of Zr content causes heterogeneity of Cu and Fe distributions,while an excessive Zr content leads to the formation of a SmCoZr impurity phase.The cellular structure and distribution of Cu concentration.gradient between the cell boundary phase and cell pha se are destroyed by inappropriate Zr content,which results in a reduction of coercivity.The Cu concentration difference between the cell boundary phase and cell phase increases with increasing Cu content.The coercivity of the Sm(Co_(bal)Fe_(0.28)Cu_yZr_(0.02))_(7.6) magnets increases from 10.4 to 25.4 kOe for y=0.05 and y=0.07.However,the excess of Cu element destroys the cell boundary phase and enlarges the cell size,resulting in a significant decrease of squareness and energy density.The optimum performance(remanence of 11.4 kG,coercivity of 2 5.4 kOe,maximum magnetic ene rgy product of 30.4 MGOe) was obtained for the Sm(Co_(0.63)Fe_(0.28)Cu_(0.07)Zr_(0.02))_(7.6) magnet.     

Influence of microstructure on tensile properties of spheroidized ultrahigh-carbon (1.8 Pct C steel

Ultrahigh-carbon steel (UHCS) containing 1.8 pct carbon was processed to create microstructures consisting of fine-spheroidized carbide particles (0.2- to 1.5-μm size range) within a fine-grained ferrite matrix (0.3- to 5-μm range) through a variety of thermomechanical processing and heat-treatment combinations. Tensile ductility, yield, and fracture strengths, and strain-hardening behavior were evaluated at room temperature. Yield strengths ranged from 640 to 1450 MPa, and uniform tensile elongation ranged from 3 to 23 pct. Quantitative analyses revealed that a Hall-Petch type relationship exists between the yield strength and the ferrite grain size and carbide particle size within grain interiors. The fracture strength, on the other hand, was found to be uniquely dependent on the coarse carbide particle size typically found at grain boundaries. Data from other investigators on spheroidized carbon steels were shown to correlate well with the data for the UHCS (1.8 pct C) material. It was shown that the tensile ductility will increase when the difference between the fracture strength and the yield strength is increased and when the strain-hardening rate is decreased. The basis for the trends observed is that the tensile ductility is limited by the fracture process that appears to be dictated by the nucleation of cracks at large carbide particles. The results obtained indicate that UHCSs have significant potential for sheet applications where high strength and good ductility are primary requirements.     

粘结相成分对Ti(C,N)基金属陶瓷组织及性能的影响

研究了以Co或Cr部分或全部代替Ni对TiC-TiN-WC-Mo-20%粘结相体系Ti(C,N)基金属陶瓷组织性能的影响。结果表明:以Co或Cr部分或全部代替Ni不会从根本上改变Ti(C,N)基金属陶瓷的组织结构,但环形相和粘结相的合金成分会有所变化;随Co或Cr含量的增加,合金的硬度增加,但强度和韧性有所下降;对于不同粘结相体系的合金,硬度相同时,以Co或Cr部分或全部代替Ni对合金断裂韧性的影响不大。     

Effect of boron on the microstructure and tensile properties of dual-phase steel

The effect of boron on the hardenability of austenite during the production of dual-phase steel and on tensile properties has been studied. Increasing boron content from 0. 0005 to 0. 0029 wt pct decreased the volume fraction of austenite present at constant intercritical annealing temperature but increased the fraction of the austenite which transformed to martensite on cooling. Increasing boron also decreased the sensitivity of martensite content to cooling rate and, therefore, of tensile properties to cooling rate. The lower volume fraction of austenite present at constant intercritical annealing temperature, and the consequentially higher carbon content of the austenite, was in agreement with the known effect of boron on the phase diagram. The previously determined effect of carbon concentration in austenite on the austenite’s martensitic hardenability was sufficient to explain the observed effects of increasing boron content. The absence of a direct effect of boron was investigated using particle-tracking autoradiography (PTA) to follow changes in boron segregation. The pattern of segregation to prior austenite grain boundaries in the initial, normalized condition dispersed slightly on holding in the (α + γ ) phase field, but no evidence was found of resegregation to α/γ interfaces. X. P. SHEN, on leave from the Central Iron and Steel Research Institute, Beijing, People’s Republic of China.     

Solidification behavior, microstructure and tensile properties of ZK60-Er magnesium alloys

ZK60-Er (erbium) alloys were made by melting ZK60 and Mg-Er magnesium alloys (20 wt.% Er) in an electric resistance furnace. The contents of Er were 0, 0.5, 1, 2, 3 wt.%, respectively. The influence of Er on solidification behavior, microstructure, corrosion resistant and mechanical properties of ZK60 magnesium alloy was studied. The results showed that long rod-like γ phase (ErZn5) formed during solidification increased with increasing Er content in the range investigated, which resulted in the decrease of the amount of galvanic couplings between phase particles and alloy matrix and the marked improvement of corrosion resistant. It was also found that elongation of the alloys decreased with increasing Er content, but tensile strength of the alloys were improved by the addition of Er due to the strengthening effect of γ phases distributing along grain boundaries.     

应变速率对电沉积纳米晶铜拉伸性能的影响

采用直流电沉积工艺,制备了平均晶粒尺寸为56nm的致密纳米晶铜.室温下进行单向拉伸实验,发现纳米晶铜的强度和韧性均随应变速率的升高而增大,特别是韧性的速率敏感十分显著.应变速率由1.04×10^-5s^-1升至1.04s^-1时,断裂应变由23.2%增至39.4%,同时抗拉强度由309MPa增至451MPa.这一现象可归因于两个方面:首先,纳米晶铜的应变硬化行为随应变速率的升高而增大,从而使其均匀变形阶段的应变增加;其次,高应变速率下纳米晶铜颈缩时发生晶粒转动,这有助于其失稳阶段的应变增加.     

退火温度对铜/铝异步冷轧复合带组织与拉伸性能的影响

采用异步冷轧复合工艺制备铜/铝复合带,研究轧后退火温度和拉伸应变速率对复合界面组织和力学性能的影响.利用扫描电镜观察界面显微组织和拉伸断口形貌,并通过线扫描分析界面元素分布,进行不同应变速率的拉伸实验研究复合带的力学性能.结果表明,较高的退火温度可促进界面扩散层的生长,在350℃时形成三层结构;退火温度的提高使复合带抗拉强度减小而延伸率增大,应变速率的提高使抗拉强度和延伸率均增大,但在退火温度超过350℃后增幅减小;退火温度和应变速率越大,复合带拉伸断口的开裂程度越大,复合界面的过渡作用越弱.     

Effects of molybdenum,phosphorus and microstructure on creep properties

The effects of molybdenum, phosphorus and of microstructure on creep were studied at 550°C utilizing the model alloys Fe—3 Cr—0.05P, Fe—3 Cr—1 Mo—0.05P and Fe—3 Cr—1 Mo. The heat treatments were varied to obtain a ferritic or bainitic structure, the effect of a preheat treatment of 300 h at 550°C was investigated. Both Mo and P increase the creep strength by different mechanisms which lead to four types of creep curves, with 1 to 3 minima. The results are discussed using microstructural information from transmission electron-microscopy.     

Effects of indium on the mechanical properties of ternary Sn-In-Ag solders

The effects of indium on the mechanical properties of ternary Sn-In-Ag solders have been reported by using tensile tests at various homologous temperatures in this study. Indium depresses the melting temperature of Sn-3.5Ag solder. However, a hard In-rich phase was formed when the indium content was raised to 15 pct, which affected the ultimate tensile strengths (UTSs) and elongation of the ternary Sn-In-Ag alloys. Their UTSs increased, but the elongation decreased by increasing the indium content. While raising the homologous temperature to η=0.796, the apparent activation energy for creep of a Sn-10In-2.8Ag alloy was about 26.9 kJ/mol. Two kinds of plastic-flow mechanisms controlled the Sn-20In-2.8Ag alloy deformation under various homologous temperature ranges. A typical intergranular creep-fracture mode was observed in the Sn-10In-2.8Ag solder. However, a dimple structure with flat plate-like facets of In-rich phase was found on the fractured surfaces of Sn-15(20)In-2.8Ag solders, which indicated that an initial crack had nucleated locally at the In-rich/γ-matrix interface.     

Interrelation of TEM microstructure,composition, tensile properties,and corrosion resistance of Al-Cu-Mg-Mn alloys

Electron microscopy was used to investigate the effects of alloying element content and quenching rate on the extent of precipitation during quenching and the resulting type of corrosion attack of naturally aged Al-Cu-Mg-Mn, Al-Cu, Al-Cu-Mg and Al-Cu-Mn alloys. Magnesium addition to Al-Cu led to S-phase (Al₂CuMg) grain boundary precipitation and development of dislocation loops of the condensed vacancy type. This appears attributable to the greater affinity of magnesium atoms for copper atoms than for vacancies. Manganese, in the presence of copper and magnesium, retarded precipitation, apparently because of its high affinity for vacancies, lowering the number of unassociated vacancies available for long range diffusion. While increasing as-quenched strengths, this association apparently has the effect of developing grain boundary regions with steep electrochemical potential gradients, which appear responsible for susceptibility of the alloy to intergranular corrosion. It is concluded that precipitation phenomena which control the hardening and corrosion behavior of these alloys are related to the relative binding energies between the several solute elements, the affinities of these individual elements for vacancies, and the ratio of the atomic concentrations of the solute elements.     

Plasma-melted nitrogen-bearing cast stainless steels—microstructure and tensile properties

Alloys of Fe-Cr-Ni and Fe-Cr-Mn were plasma arc-melted and chill cast in the form of ingots. Exposure of liquid melts to a nitrogen plasma for the purpose of adding nitrogen to the above alloys was used to dissolve varying amounts (up to 0.32 wt pct) of nitrogen. Carbon and sulfur were varied up to 0.5 and 0.056 wt pct, respectively. The alloys were evaluated for their monotonic behavior. It was observed that while strength and ductility parameters increased considerably with increasing nitrogen and carbon contents, both these parameters deteriorated with sulfur content. The analysis of the present results, along with the data from the literature, suggests that the strength parameters are predominantly chemistry dependent, particularly controlled by the nitrogen and carbon contents. The results also show that the alloys produced by this relatively new technique, plasma arc-melting, are comparable to those produced by other standard techniques. A.K. SINGH, formerly Postdoctoral Fellow, Department of Metallurgical Engineering, Institute of Technology, Banaras Hindu University.     

固溶温度对GH4202合金组织及拉伸性能的影响

为充分挖掘沉淀强化型镍基高温合金GH4202管材性能,以满足我国航天新型发动机的要求,研究了固溶处理温度对合金组织及拉伸性能的影响规律.结果表明,在1 050~1 075℃范围固溶处理后合金晶粒度无明显变化,当固溶温度升至1 100℃时,合金局部出现异常晶粒长大,当固溶温度达到1 150℃时,合金晶粒均匀长大.随固溶温度升高,合金晶界硼、碳化物数量明显减少,由链状向孤立的颗粒状转变.随固溶温度升高,GH4202合金室温及高温拉伸强度均呈降低趋势,尤其以屈服强度降低幅度最为显著.合金的室温面缩率随固溶温度升高而降低,且降低幅度较大,但室温断裂延伸率变化并不显著;700℃下合金的断面收缩率与断裂延伸率随固溶温度的变化均表现为先升高后降低的趋势.GH4202合金最佳固溶处理工艺为1 110℃保温30 min后水冷,此时合金晶粒度为5.0级、晶界碳化物呈细小链状,晶内沉淀强化γ'相弥散析出,可保证合金具有优异的室温及高温力学性能.     

Influence of test temperature and microstructure on the tensile properties of titanium alloys

Tensile tests were performed between room temperature and 500 °C on age-hardened Ti-Al and Ti-6A1-4V alloys to study the effect of various microstructural parameters on the temperature dependence of the yield stress. It was found that the concentration of interstitial solute atoms is responsible for the strong temperature dependence of the yield stress. Small interstitial concentrations increase the yield stress significantly at low test temperatures, while this hardening effect almost disappeared at temperatures above about 300 °C. Through variations of degree of age-hardening, grain size, texture, phase morphology, and phase dimensions of (α + β) microstructures, the absolute yield stress values were changed by constant amounts over the test temperature range without changing significantly the temperature dependence. The yield stress increased by increasing the degree of age-hardening, by decreasing the grain size or phase dimensions, by texture hardening, and by choosing equiaxed instead of lamellar phase morphologies.     

合金成分对高温Sm(Co,Fe,Cu,Zr)z磁性能与显微组织的影响

用粉末冶金法制备了6种Sm(CobalFe0.1CuyZr0.04)z烧结磁体,每种成分磁体都进行了热处理工艺优化实验;并对合金成分对磁体的显微组织及磁性能的影响进行了研究。结果表明:z值较小的磁体有较多的1∶5相,室温的Br、Hci与(BH)max都较低些,但方形度(K)较好,因此适当减小z值有利于提高高温磁性能;Cu含量的增加使1∶5相的畴壁能(1γ∶5)减少,2∶17相与1∶5相的畴壁能差(Δγ)增加,从而使矫顽力增加,但Cu含量太高,如果不同时增加Sm含量,将导致Br与(BH)max急剧下降;z值较低,同时Cu含量又较高的Sm(CobalFe0.1-Cu0.16Zr0.04)6.7磁体具有最佳室温磁性能与方形度。