Mechanical Property and Microstructure of Oxide Dispersion Strengthened Nickel-base Superalloy MA758

ＭｅｃｈａｎｉｃａｌＰｒｏｐｅｒｔｙａｎｄＭｉｃｒｏｓｔｒｕｃｔｕｒｅｏｆＯｘｉｄｅＤｉｓｐｅｒｓｉｏｎＳｔｒｅｎｇｔｈｅｎｅｄＮｉｃｋｅｌｂａｓｅＳｕｐｅｒａｌｏｙＭＡ７５８ＳｈａＷｅｉ（沙维）ＤｅｐａｒｔｍｅｎｔｏｆＣｉｖｉｌＥｎｇｉｎｅｅｒｉ...     

Recrystallization in Oxide Dispersion Strengthened Nickel－base Superalloy MA760

ＲｅｃｒｙｓｔａｌｌｉｚａｔｉｏｎｉｎＯｘｉｄｅＤｉｓｐｅｒｓｉｏｎＳｔｒｅｎｇｔｈｅｎｅｄＮｉｃｋｅｌ－ｂａｓｅＳｕｐｅｒａｌｌｏｙＭＡ７６０ＳｈａＷｅｉ（沙维）（ＥｅｐａｒｔｍｅｎｔｏｆＣｉｖｉｌＥｎｇｉｎｅｅｒｉｎｇ，ＴｈｅＱｕｅｅｎ＇ｓＵｎｉ...     

Characterisation of a Mechanically Alloyed Oxide Dispersion Strengthened Niekel－base Superalloy

ＣｈａｒａｃｔｅｒｉｓａｔｉｏｎｏｆａＭｅｃｈａｎｉｃａｌｌｙＡｌｌｏｙｅｄＯｘｉｄｅＤｉｓｐｅｒｓｉｏｎＳｔｒｅｎｇｔｈｅｎｅｄＮｉｅｋｅｌ－ｂａｓｅＳｕｐｅｒａｌｌｏｙＳｈａＷｅｉ（沙维）ＤｅｐｅｒｔｍｅｎｔｏｆＭａｔｅｒｉａｌｓＳｃｉｅｎｃｅａ...     

Stress－rupture Property and Microstructure of Yttria Dispersion Strengthened Alloy MA956

Ｓｔｒｅｓｓ－ｒｕｐｔｕｒｅＰｒｏｐｅｒｔｙａｎｄＭｉｃｒｏｓｔｒｕｃｔｕｒｅｏｆＹｔｔｒｉａＤｉｓｐｅｒｓｉｏｎＳｔｒｅｎｇｔｈｅｎｅｄＡｌｌｏｙＭＡ９５６ＳｈａＷｅｉ（沙维）（ＤｅｐａｒｔｍｅｎｔｏｆＣｉｖｉｌＦｎｇｉｎｅｅｒｉｎｇ，ＴｈｅＱｗｅ...     

Recrystallization in Oxide Dispersion Strengthened Nickelbase Superalloy MA760

ＲｅｃｒｙｓｔａｌｉｚａｔｉｏｎｉｎＯｘｉｄｅＤｉｓｐｅｒｓｉｏｎＳｔｒｅｎｇｔｈｅｎｅｄＮｉｃｋｅｌｂａｓｅＳｕｐｅｒａｌｏｙＭＡ７６０ＳｈａＷｅｉ（沙维）ＤｅｐａｒｔｍｅｎｔｏｆＣｉｖｉｌＥｎｇｉｎｅｒｉｎｇ，ＴｈｅＱｕｅｅｎ′ｓＵｎｉｖｅｒｓ...     

Laser Treatment of Oxide Dispersion Strengthened Alloys

ＬａｓｅｒＴｒｅａｔｍｅｎｔｏｆＯｘｉｄｅＤｉｓｐｅｒｓｉｏｎＳｔｒｅｎｇｔｈｅｎｅｄＡｌｌｏｙｓＳｈａＷｅｉ（沙维）（ＤｅｐａｒｔｍｅｎｔｏｆＭａｉｅｒｉａｌｓＳｃｉｃｎｃｅａｎｄＭｅｔａｌｌｕｒｇｙ，ＵｎｉｖｅｒｓｉｔｙｏｆＣａｍｂｒｉｄｇｅ，Ｕ...     

Diffusion Brazing of Mechanically Alloyed Oxide Dispersion Strengthened Materials

ＤｉｆｆｕｓｉｏｎＢｒａｚｉｎｇｏｆＭｅｃｈａｎｉｃａｌｌｙＡｌｌｏｙｅｄＯｘｉｄｅＤｉｓｐｅｒｓｉｏｎＳｔｒｅｎｇｔｈｅｎｅｄＭａｔｅｒｉａｌｓＳｈａＷｅｉ（沙维）（ＤｅｐａｒｔｍｅｎｔｏｆＣｉｖｉｌＥｎｇｉｎｅｅｒｉｎｇ，ＴｈｅＱｕｅｅｎ′ｓＵｎ...     

Microstructure and Mechanical Property of Ni Metal Treated by Surface Mechanical Attrition

A nanostructured surface layer can be formed in Ni metal treated by surface mechanical attrition (SMA). The microstructure was investigated by using optical microscope, X-ray diffractometer and transmission electron microscope,respectively. Mechanical property measurements indicate that the yield strength of the surface layer raises significantly while the tensile strength somewhat changes and the elongation percentage reduces severely compared with that of the inside layer. Meanwhile, yield-drop-like phenomenon occurs in the surface layer after SMA treatment. In order to compare the mechanical behavior of nanostructured materials with two phases, Fe-30Ni nanostructured alloy was also investigated.     

Modification of Recrystalization Grain Structure of Ytria Dispersion Strengthened MA956 Alloy by Pre-deformation

ＭｏｄｉｆｉｃａｔｉｏｎｏｆＲｅｃｒｙｓｔａｌｉｚａｔｉｏｎＧｒａｉｎＳｔｒｕｃｔｕｒｅｏｆＹｔｒｉａＤｉｓｐｅｒｓｉｏｎＳｔｒｅｎｇｔｈｅｎｅｄＭＡ９５６ＡｌｏｙｂｙＰｒｅｄｅｆｏｒｍａｔｉｏｎＳｈａＷｅｉ（沙维）ＤｅｐａｒｔｍｅｎｔｏｆＣｉｖｉ...     

Recent Progress of Oxide/Carbide Dispersion Strengthened W-Based MaterialsEI北大核心CSCD

Tungsten (W) plays an important role in the defense industry, aerospace and nuclear industry due to its excellent properties such as high melting point (3410.), high density (19.35 g/cm(3)), high hardness, high elastic modulus, high thermal conductivity, low expansion coefficient and low vapor pressure. However, its disadvantages, such as low temperature brittleness (ductile brittle transition temperature usually above 400 degrees C), low tensile strength, recrystallization embrittlement, high thermal load induced cracking and irradiation embrittlement, affected seriously its processing and servicing performance. Focusing on these problems, carbides/oxide dispersion strengthened W alloys were studied widely. The mechanical properties and other service properties of W were significantly improved by nano scale carbide/oxide dispersion strengthening and microstructure optimization. This article mainly reviews carbide and oxide dispersion strengthening design and the corresponding W-based materials preparation, microstructure and properties of regulation and service performance evaluation, introduces the latest progress of the research and development of the authors' team, and looks forward to the future development trend and the problems to be solved.     

Microstructure and Mechanical Properties of a Spray-Formed Superalloy

The microstructural evolution and mechanical properties of a spray-formed superalloy were studied in this paper. Based on a better understanding of the microstructural evolution of the spray-formed superalloy during solution treatment, an optimum solution treatment process was obtained, namely, at 1,140 °C for 6 h, and air cooling(AC). The effects of the ageing treatments on the mechanical properties of the post-solution-treated spray-formed superalloy were evaluated using ageing harden curves and tensile testing. The results indicated that the maximum hardness value was achieved at 850 °C for 8 h, AC. Due to co-precipitation of primary and secondary c0 precipitates during the heat treatment,the spray-formed superalloy obtained an excellent combination of yield strength(YS = 1,110 MPa), ultimate tensile strength(UTS = 1,503 MPa), ductility(elongation, EL = 21%) and excellent stress rupture properties at 650 °C(UTS = 1,209 MPa, EL = 15.8%). The heat treatment also improved the rupture life at 650 °C/950 MPa and 750 °C/539 MPa up to 140 h without rupturing. The tensile-fractured surfaces exhibit ductile transgranular failure feature. The optimum heat treatment process was determined to be 1,140 °C/6 h+850 °C/8 h+AC.     

Sn effect on microstructure and mechanical properties of ultrafine eutectic Ti–Fe–Sn alloys

Microstructural investigations on ultrafine eutectic (Ti₆₅Fe₃₅)_100−xSn_x alloys with x = 0, 1 and 3 at.% reveal that additional Sn is effective to control formation of the micron-scale dendrites and to decrease the length-scale of lamellar spacing with enhancing macroscopic plasticity at room temperature compression. Hence, it is possible to understand the influence of the microstructural change on the plasticity of the ultrafine eutectic Ti–Fe–Sn alloys.     

FGH4113A合金的双性能热处理组织与力学性能研究

利用扫描电子显微镜（Scanning Electron Microscope,SEM）、光学显微镜（Optical Microscope,OM）、拉伸、蠕变、疲劳试验机等研究了一种新型镍基粉末高温合金FGH4113A（WZ-A3）在两种热处理状态下的显微组织和力学性能,为双性能热处理研究提供组织与力学性能依据。结果表明：FGH4113A合金在双性能热处理中,过固溶与亚固溶态组织与力学性能具有明显的双模特性;室温下,亚固溶态相比过固溶态屈服强度高10.6%,800℃下,过固溶态相比亚固溶态屈服强度高11.7%;与同样是亚固溶或过固溶的其它合金相比,FGH4113A的拉伸强度优于ME3合金,与LSHR合金相当;FGH4113A合金在750℃/450MPa的蠕变变形以位错滑移机制主导,弥散分布的小尺寸硼化物有助于蠕变性能的提高,其蠕变性能全面超过ME3合金,与LSHR合金相当;过固溶态的粗晶组织在裂纹扩展中具有更长的滑移带,在循环载荷中具有较低的累积损伤,抗裂纹扩展能力优于亚固溶态;过固溶态的裂纹扩展断口呈现穿晶断裂特征,亚固溶态由于细晶粒边界的一次γˊ的存在降低了晶界的抗裂纹扩展能力,断口较粗糙,呈现沿晶-穿晶混合断裂特征。     

Influences of different prior heat treatments on the microstructural and mechanical properties of Cu-Fe filamentary composites

Cu-6 wt.% Fe and Cu-12 wt.% Fe filamentary composites were prepared by casting and cold drawing. And a different heat treatment of quenching and aging or homogenizing was introduced before cold drawing process, respectively. The microstructure was observed and the tensile strength measured for the composites at different drawing strains. The quenching and aging or homogenizing prior to drawing deformation refine the as-cast microstructure and result in the increase in interface density in the drawn microstructure. The drawn alloys with the homogenizing treatment show smaller filament spacing than those with the quenching and aging treatment because homogenizing results in smaller and more dispersive primary Fe dendrites before drawing deformation. The heat treatments can improve the strength of the composites by increasing precipitation strengthening and interface strengthening levels. With the reduction in filament spacing during drawing deformation, the strength of the alloys with smaller initial size of Fe dendrites increases more obviously.     

Effect of soldering condition on formation of intermetallic phases developed between Sn-0.3Ag-0.7Cu low-silver lead-free solder and Cu substrate

In this paper, effect of soldering time and temperature on formation of intermetallic compounds developed between Sn-0.3Ag-0.7Cu lead-free solder and copper substrate was investigated. Dip soldering was performed at 250, 270, and 290 °C with soldering time of 5, 10, 15, and 20 s. Either ?-Cu₃Sn or η-Cu₆Sn₅ intermetallic phase was found at the interface between the solder and the substrate depending on the soldering condition, i.e., soldering time and soldering temperature. ?-Cu₃Sn was found only when the substrate was soldered at 250 °C for 5 and 10 s. At other soldering conditions, only η-Cu₆Sn₅ was found at the interfacial zone. Crystal structure of ?-Cu₃Sn intermetallic phase was orthorhombic, and it was hexagonal structure for η-Cu₆Sn₅. Transformation of the intermetallic phases was also discussed.     

Cu + TiB2 composite filler for brazing Al2O3 and Ti-6Al-4V alloy

Al₂O₃ and Ti-6Al-4V alloy were brazed using Cu + TiB₂ composite filler, which manufactured by mechanical milling of Cu and TiB₂ powders. Typical interface microstructure of joint was Al₂O₃/Ti₄(Cu,Al)₂O/Ti₂Cu + Ti₃Al + Ti₂(Cu,Al)/Ti₂(Cu,Al) + AlCu₂Ti/Ti₂Cu + AlCu₂Ti + Ti₃Al + Ti₂(Cu,Al) + TiB/Ti(s.s) + Ti₂Cu/Ti-6Al-4V alloy. Based on temperature- and time-dependent compositional change, the formation of intermetallics in joint was basically divided into four stages: formation of interfacial Ti₄(Cu,Al)₂O in Al₂O₃ side, formation of Ti₂Cu, Ti₃Al, TiB, Ti₂Cu, and AlCu₂Ti in layers II and IV, formation of Ti₂(Cu,Al) and AlCu₂Ti in layer III, formation of Ti + Ti₂Cu hypereutectoid organization adjacent to Ti-6Al-4V alloy. TiB in situ synthesized in joint not only acted as low thermal expansion coefficient reinforcement to improve the mechanical properties at room temperature, but also as skeleton ceramic of joint to increase high temperature mechanical properties of Al₂O₃/Ti-6Al-4V alloy joint increasing. When the joint containing 30 vol.% TiB brazed at 930 °C and 10 min of holding time, the maximum room temperature shear strength of joint was 96.76 MPa, and the high temperature shear strength of joint was 115.16 MPa at 800 °C.     

Improving the strength of brazed joints with in situ synthesized TiB whiskers

TiB whiskers have been in situ synthesized as reinforcements in 73Cu-27Ti (wt.%) active brazing filler alloy used for the joining of Al₂O₃ and Ti-6Al-4V alloy. The results show that TiB whiskers served as an effective reinforcement phase aid to decrease the residual stress and increase the shear strength of joints. The shear strength of the joint, containing 30 vol.% TiB whiskers was about 239% higher than that of the joint brazed without TiB whiskers.