Influence of minor elements additions on microstructure and properties of 93W-4·9Ni-2·1Fe alloys

Effects of elements rhenium and chromium additions on properties and microstructure of 93W-4·9Ni-2·1Fe alloys were investigated. Optical microscope (OM), scanning electron microscope (SEM) and EDAX energy spectrometer were used to characterize the microstructure and compositions of the alloys, respectively. The tensile strength and elongation of alloys were evaluated using the quasi-static tensile testing machine, and the relative densities of the alloys were evaluated using the Archimedes water immersion method. The experimental results indicated that when elements Re and Cr were in the range of 0–1·0 wt.%, relative density, elongation, tensile strength of 93W-4·9Ni-2·1Fe alloys varied from 99·4%, 26·4%, 997·2 MPa without Re additions to 99·5%, 8·6%, 1161·2 MPa with 1·0 wt.% Re addition, respectively. Rhenium generated solid-solution strengthening, grain refinement, reducing ductile tearing and increasing transcrystalline fracture, which resulted in the ductility reduction and the strength increase of the heavy alloys. With the increase of Cr content from 0–1·0 wt.%, the tensile strength, relative density and elongation of 93W-Ni-Fe alloy reduced from 997·2 MPa, 99·3%, 15% to 844·4 MPa, 95·2%, 5·7%, respectively. Element Cr formed interphases with elements W, Ni, Fe and O and gathered along the interface of the alloys, which induced interfacial cohesion and resulted in lower mechanical properties of 93W-Ni-Fe alloys.     

钛铝合金薄板成形技术的发展及应用研究

介绍了TiAl基合金薄板的铸造冶金工艺、元素粉合成工艺、合金粉成形工艺及单元素箔板叠轧工艺4大类成形技术.评述了国内外TiAl基合金薄板成形技术的发展现状,以及TiAl基合金薄板在航空航天领域应用研究状况.指出TiAl基合金的研究重点已经从基础研究转向应用基础研究,其实用化研究进程正在加快.     

TiAl基合金超塑性变形的力学行为研究

采用恒应变速率和应变速率递增实验研究了变形态Ti-48Al-2.3Cr-0.2Mo(at%)合金的超塑性变形力学行为,并根据计算得到的变形激活能,结合超塑性变形的流变曲线形态,对TiAl基合金的超塑性变形机理进行了分析。超塑性拉伸试验分别在800~900℃区间和950~1100℃区间和应变速率ε=1×10-35×10-5 s-1的条件下进行。结果表明,变形态TiAl基合金超塑性变形的应变-应力曲线上几乎没有稳态塑性流变阶段。在950~1100℃区间,加工硬化现象显著。当T>1025℃或ε≤5×10-4 s-1时,应力-应变曲线呈典型的加工硬化形态,并且随着变形温度升高和应变速率降低,加工硬化阶段增长。原始组织中的高密度位错是引起加工硬化的原因。在800~900℃区间,应变速率敏感性因子m的最佳值在0.52~0.67之间,超塑性变形的表观激活能为Qapp=178 kJ/mol,晶界扩散是超塑性的速率控制机制。在950~1100℃区间,m的最佳值在0.63~0.77之间,超塑性变形的表观激活能值Qapp=290 kJ/mol,晶格扩散是超塑性变形的速率控制机制。     

Mechanism of reaction synthesis of Li-B alloys

Li-B alloy[1] has greater specific capacity, more negative potential and greater specific power than the well-known anode materials of thermal battery[24]. As a promising anode material for the thermal battery, the Li-B alloy is in nature a composite that consists of porous and refractory Li-B compound frame and metal Li filled in the porosity. That is why it can be kept in solid state at above 600℃, with the electrochemical properties very similar to those of pure Li. Though its applicati…     

FHA BIOCERAMIC COMPOSITE MATERIALS ENHANCED BY ZrO_2

ＦＨＡＢＩＯＣＥＲＡＭＩＣＣＯＭＰＯＳＩＴＥＭＡＴＥＲＩＡＬＳＥＮＨＡＮＣＥＤＢＹＺｒＯ＿２ＦＨＡＢＩＯＣＥＲＡＭＩＣＣＯＭＰＯＳＩＴＥＭＡＴＥＲＩＡＬＳＥＮＨＡＮＣＥＤＢＹＺｒＯ＿２￥ＲｕａｎＪｉａｎｍｉｎ；ＨｕａｎｇＢａｉｙｕｎ（ＰｏｗｄｅｒＭｅ...     

元素粉法制备TiAl基合金板材

综述了元素粉法制备TiAl基合金板材的工艺和致密化机理,分析了影响反应合成致密化的因素,介绍了板材的性能和后续处理,指出了该工艺的局限性和发展方向.