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1.
《中国有色金属学会会刊》2020,30(8):2079-2089
The effects of Sn content on microstructure and tensile properties of as-cast and as-extruded Mg−8Li−3Al− (1,2,3)Sn (wt.%) alloys were investigated by X-ray diffractometry (XRD), optical microscopy (OM), scanning electron microscopy (SEM) and tensile test. It is found that, as-cast Mg−8Li−3Al−(1,2,3)Sn alloys consist of α-Mg+β-Li duplex matrix, MgLiAl2 and Li2MgSn phases. Increasing Sn content leads to grain refinement of α-Mg dendrites and increase in content of Li2MgSn phase. During hot extrusion, complete dynamic recrystallization (DRX) takes place in β-Li phase while incomplete DRX takes place in α-Mg phase. As Sn content is increased, the volume fraction of DRXed α-Mg grains is increased and the average grain size of DRXed α-Mg grains is decreased. Increasing Sn content is beneficial to strength but harmful to ductility for as-cast Mg−8Li−3Al−(1,2,3)Sn alloys. Tensile properties of Mg−8Li−3Al− (1,2,3)Sn alloys are improved significantly via hot extrusion and Mg−8Li−3Al−2Sn alloy exhibits the best tensile properties. 相似文献
2.
对比研究天然中砂和混合砂清水混凝土的工作性、物理力学性能、外观质量、收缩和抗渗性能.试验结果表明:机制砂和特细砂按适当比例混合.可以配制出性能高、外观质量好的C50清水混凝土. 相似文献
3.
采用普通铸造法在真空中频熔炼炉中制备了Al63Cu25Fe12准晶合金试样,利用光学显微镜、扫描电镜、能谱分析仪和X衍射衍射仪,分析了准晶相和其它类似相的微观组织及相的变化。结果表明:铸态Al63Cu25Fe12准晶合金主要由λ相、I相、β相和其它微量相组成;采用各部位冷却速度不同的圆台式浇铸模具对合金进行浇铸,冷却速度较快的铸锭底部准晶I相的含量低于冷却速度较慢的铸锭顶部;Al63Cu25Fe12准晶合金经过750℃×8 h的退火处理后,λ相、β相及其它微量相有向准晶I相变化的趋势。 相似文献
4.
采用真空感应炉熔炼制备Ag-9.89%Y二元合金棒,借助金相显微镜、扫描电镜、X射线衍射仪和电子探针研究分析合金的铸态组织特征。结果表明,Ag-Y合金中存在块状和方形环状的初生Ag51Y14化合物相,以初生Ag51Y14相为中心形成向四周发散呈鱼鳞状交替分布的共晶组织。初生Ag51Y14相中的钇含量高于共晶Ag51Y14相。初生Ag51Y14相边界局部直接生长出共晶组织,局部围绕银固溶体组织,环状初生Ag51Y14组织里侧和外侧组织结构相似。共晶组织片层细小,平行生长方向组织呈层片状,垂直生长方向组织呈点状,2种区域含有相同的银和钇含量。 相似文献
5.
《Intermetallics》2014
In this study, the nano-crystalline Nitinol (50.9 at.% Ni) was prepared by 40% cold deformation. Subsequently it was subjected to 15-min-heat treatments at 300–550 °C. Changes of the structure and mechanical properties were studied by transmission electron microscopy, micro X-ray diffraction, differential scanning calorimetry, Vickers hardness measurements, tensile and bend-type fatigue testing. It was shown that the cold drawn material contains textured nano-crystalline B2 grains of 50 nm in thickness and a high concentration of lattice defects. Its tensile strength, hardness and fatigue life were 1521 MPa, 421 HV0.05 and 2435 bending cycles to fracture, respectively. After heat-treatment up to 450 °C/15 min the material underwent Ni4Ti3 precipitation and partial recovery processes. Heat-treatments at above 450 °C induced recrystallization, grain and precipitate growth. Hardness and fatigue lives showed maxima of 692 HV0.05 and 5883 cycles, respectively, after heat-treatments at 450 °C/15 min. In contrast, both tensile strength and B2 → B19′ transformation stress decreased with increasing heat-treatment temperature, but a decrease of the tensile strength after heat-treatments at 300–450 °C was slow (tensile strength after heat-treatment at 450 °C/15 min was 1486 MPa). The observed variations of mechanical characteristics were discussed in relation to structural changes observed. 相似文献
6.
《Intermetallics》2014
Investment cast Ti45Al2Mn2Nb1B with fine lamellar microstructures was subject to fatigue crack propagation testing at 650 °C and a stress ratio of R = 0.1. The fracture surfaces were examined under SEM and the observed features are correlated with both stress intensity range (ΔK) and lamellar orientation. Translamellar fracture is primary fracture mode for most of the lamellar orientations. Interlamellar fracture is influenced by a combination of the ΔK and lamellar orientation. At low ΔK only the lamellar colonies with their lamellar interfaces almost perpendicular to the stress axis fractured via interlamellar fracture mode. At high ΔK interlamellar fracture can occur in lamellar colonies with any orientations. 相似文献
7.
In the present study, creep properties of as-cast Mg-5Al-5Ca-2Sn(AXT552) alloy were investigated by means of a GWT304 creep testing machine at temperatures of 175 °C and 200 °C in the stress range of 35-90 MPa. Results show that creep rates increase with applied stress at an identical temperature. Creep strain at 100 hours is 0.0518% and 0.083% at creep conditions of 175°C/75 MPa and 200°C/60 MPa, respectively, which is comparable to MRI230 D and much lower than most of AX series alloys. By the observation and analysis for samples before and after creep tests using a Shimadzu XRD-7000 type X-ray diffractometer(XRD) and a Hitachi S-3400 N type scanning electron microscope(SEM), it was found that Al_2Ca(C15) phase precipitated out of C36 phase or matrix. The cavity formation and connection at the interface of soft matrix and hard intermetallics caused the propagation of cracking along the eutectic phase during creep process and dislocation accommodated grain/phase boundary sliding is expected to be the dominant creep mechanism. 相似文献
8.
通过试验研究,探讨添加钒钛微合金化对铸态中锰钢的组织性能的影响,确定钒钛微合金的合适加入量,实验表明经添加V质量分数为0.1%。0.2%或Ti0.15%与稀土和硅钙合金的复合处理后的铸态中锰钢,在中低冲击载荷下耐磨性能优于高锰钢,实现铸态中锰钢在中低冲击载荷下使用具有良好的耐磨性,该项目的研究具有良好的经济与社会效益。 相似文献
9.
2D70耐热铝合金铸态组织研究 总被引:2,自引:1,他引:1
利用光学显微镜、扫描电子显微镜、能谱分析、X射线物相分析、透射电子显微镜研究了2D70耐热铝合金半连续铸锭的铸态组织.研究结果表明:2D70耐热铝合金铸态组织为粗大枝晶组织,枝晶间蜂窝状共晶相为AL,A12CuMg/A12Cu,合金中含有大量块状相和条状相,能谱分析显示为含Fe,Ni相,铸态合金中Cu,Fe,Ni元素偏析严重.合金铸态相主要为а(Al),S(Al2CuMg),0(Al2Cu),Al7Cu2Fe,Al7Cu4Ni,Al9FeNi相. 相似文献
10.