共查询到10条相似文献,搜索用时 114 毫秒
1.
Bulk Zr2Al4C5 ceramics was synthesized by an in situ reactive hot-pressing process using ZrC, Al and carbon black as staring materials. The reaction path of synthesis was discussed based on differential thermal analysis, Raman spectra and X-ray diffraction results. Compared with the reported Zr2Al3C4, Zr2Al4C5 has a relatively high hardness (Vickers hardness of 12.2 GPa), superior strength (flexural strength of 420 MPa) and lower electrical resistivity (1.05 μΩ m). In addition, the room-temperature thermal conductivity value, 14.6 W (m K)?1 for Zr2Al4C5, was smaller than the value for Zr2A3C4 ceramics (15.5 W (m K)?1), and the heat capacity of Zr2Al4C5 is much higher than that of Zr2A3C4 in the overall temperature range. The results here indicated that Zr2Al4C5 is a potential high-temperature structural ceramic. 相似文献
2.
In this study polycrystalline specimens of as-cast DyCu with B2 crystal structure were compressed to different strains at room temperature to test if stress-induced phase transformation and twinning occur during deformation. In these tests DyCu exhibited high ductility with plastic strain as high as 35% and ultimate compressive strength of ∼790 MPa. X-ray diffraction and transmission electron microscopy (TEM) showed no indications that DyCu had undergone stress-induced phase transformation or twinning. 〈1 1 1〉-type dislocations have been observed to play an important role for imparting the ductile behavior. TEM analyses showed the presence of second phases, Dy2O3 and DyCu2 within the DyCu. The mechanisms of ductility and impurity phase formation are discussed. 相似文献
3.
Microstructures and mechanical properties of as‐cast titanium–zirconium–molybdenum ternary alloys 下载免费PDF全文
C.D. Yang S.P. Wang J.J. Shi C.H. Wang Z.M. Ren G.H. Cao 《Materialwissenschaft und Werkstofftechnik》2018,49(1):30-38
In this study titanium–zirconium–molybdenum alloys (Ti50Zr50)100‐xMox (xMo; x = 0 at.%, 1 at.%, 3 at.%, 5 at.% or 7 at.%) were investigated, focusing on the effect of molybdenum addition on their microstructures and mechanical properties. Transmission electron microscopy observations revealed that the binary Ti50Zr50 alloy was composed entirely of an acicular hexagonal structure of the α’ phase. When the molybdenum content was 1 at.%, the alloy was composed of β and ω phases. However, when 3 at.% or more molybdenum was added, only the equiaxed, retained β phase was observed. Tensile tests at room temperature indicated that the mechanical properties of the 1Mo alloy were inferior owing to the embrittlement effects of the ω phase and the difficulty of dislocation motion through the ω phase. Our research suggested that the 5Mo alloy had excellent ductility (16.5 %) as well as adequate strength (780 MPa). The improved mechanical properties were attributed to the enhanced stability of the β phase and the disappearance of the ω phase. 相似文献
4.
Microstructure and Mechanical Properties of Al25 − xCr25 + 0.5xFe25Ni25 + 0.5x (x = 19, 17, 15 at%) Multi‐Component Alloys 下载免费PDF全文
5.
Achieving high mechanical strength and ductility in age-hardenable Al7000 series (Al–Zn–Mg) alloys fabricated by selective laser melting (SLM) remains challenging. Here, we show that crack-free AlZnMgCuScZr alloys with an unprecedented strength–ductility synergy can be fabricated via SLM and heat treatment. The as-built samples had an architectured microstructure consisting of a multimodal grain structure and a hierarchical phase morphology. It consisted of primary Al3(Scx,Zr1−x) particles which act as inoculants for ultrafine grains, preventing crack formation. The metastable Mg-, Zn-, and Cu-rich icosahedral quasicrystals (I-phase) ubiquitously dispersed inside the grains and aligned as a filigree skeleton along the grain boundaries. The heat treated SLM-produced AlZnMgCuScZr alloy exhibited tunable mechanical behaviors through trade-off among the hierarchical features, including the dual-nanoprecipitation, viz, η′ phase, and secondary (Al,Zn)3(Sc9Zr), and grain coarsening. Less coarsening of grains and (Al,Zn)3(Sc9Zr) particles, due to a reduced solution treatment temperature and time, could overwhelm the more complete dissolution of I-phase (triggering more η′ phase), resulting in higher yield strength. Optimal combination of the hierarchical features yields the highest yield strength (∼647 MPa) among all reported SLM-produced Al alloys to date with appreciable ductility (∼11.6%). The successful fabrication of high-strength Al7000 series alloys with an adjustable hierarchical microstructure paves the way for designing and fine-tuning SLM-produced aluminum engineering components exposed to high mechanical loads. 相似文献
6.
(Cu42Zr42Al8Ag8)100? x Si x (x?=?0?~?1) amorphous alloy rods of 2–6?mm diameter were prepared by Cu-mold drop casting. The thermal properties, microstructure evolution, and mechanical properties were studied by differential scanning calorimetry (DSC), X-ray diffractometry (XRD), transmission electron microscopy (TEM), hardness test, and compression test. The XRD result revealed that all as-quenched (Cu42Zr42Al8Ag8)100?x Si x alloy rods exhibited a broad diffraction pattern in the amorphous phase. The (Cu42Zr42Al8Ag8)99.5Si0.5 alloy was found to possess the highest glass forming ability (GFA) as well as the best thermal stability among all tested samples. In addition, both its hardness and yield strength were increased by the microalloyed Si content. The fracture strength and the plastic strain of (Cu42Zr42Al8Ag8)99.5Si0.5 amorphous alloy can reach 2000?MPa and 3.5 %. 相似文献
7.
Zhichao Zhu Mingliang Wang Tao He Tianxin Li Yan Di Hongwei Yan Yongan Zhang Yiping Lu 《Advanced Engineering Materials》2023,25(20):2300689
L12 phase hardening alloys with excellent mechanical properties are of great significance for structural applications. However, low volume fractions of L12 precipitates in conventional alloys (nearly lower than 60%) tend to limit their practical usage, while the strengths of the alloys generally increase with L12 precipitation contents. Herein, a novel high-entropy alloy (HEA) Ni35Co35Fe10Al8Ti10B2 with ultrahigh concentration L12 precipitates is successfully designed aided by the calculation of phase diagrams (CALPHAD). The volume fraction of L12 precipitates in this HEA is up to 75% and outperforms that of most of traditional superalloys. The novel L12-strengthened Ni35Co35Fe10Al8Ti10B2 has an ultrahigh tensile yield strength of ≈1.45 GPa, ultimate tensile strength of ≈1.9 GPa, and great ductility of ≈23% at room temperature. The desirable strength–ductility combination is superior to most of conventional superalloys and reported HEAs, mainly due to the presence of ultrahigh concentration L12 precipitates that act as dislocation obstacles and the formation of numerous stacking faults and deformation twining. This work is expected to provide guidance for developing new high-performance HEAs with an excellent combination of strength and ductility. 相似文献
8.
Gang Qin Shu Wang Ruirun Chen Xue Gong Liang Wang Yanqing Su Jingjie Guo Hengzhi Fu 《材料科学技术学报》2018,34(2):365-369
Nb has a positive effect on improving the mechanical properties of metal materials, and it is expected to strengthen CoCrCuFeNi high-entropy alloys (HEAs) with outstanding ductility and relatively weak strength. In this paper, the alloying effects of Nb on the microstructural evolution and the mechanical properties of the (CoCrCuFeNi)100-xNbx HEA were investigated systematically. The result shows that Nb promotes the phase transition from FCC (face-centered cubic) to Laves phase, and the volume fractions of Laves phase increase from 0% to 58.2% as the Nb content increases. Compressive testing shows that the addition of Nb has a positive effect on improving the strength of CoCrCuFeNi HEA. The compressive yield strength of (CoCrCuFeNi)100-xNbx HEAs increases from 338 MPa to 1322 MPa and the fracture strain gradually reduces from 60.0% (no fracture) to 8.1% as the Nb content increases from 0 to 16 at.%. The volume fraction increase of hard Laves phase is the key factor for the strength increase, and the reduction of the VEC (valence electron concentration) value induced by the addition of Nb is beneficial for the increase of the Laves phase content in these alloys. 相似文献
9.
Libo Gao Jian Song Zengbao Jiao Weibing Liao Junhua Luan James Utama Surjadi Junyang Li Hongti Zhang Dong Sun Chain Tsuan Liu Yang Lu 《Advanced Engineering Materials》2018,20(1)
10.
《Advanced Powder Technology》2022,33(3):103520
Body-centered-cubic (BCC) high entropy alloys (HEAs) usually exhibit high strength but poor ductility. To overcome such strength-ductility trade-off, a novel (FeCr)45(AlNi)50Co5 HEA was presented in this paper, which was designed and fabricated with mechanical alloying (MA) followed by spark plasma sintering (SPS), and has a heterogeneous microstructure with multi-scale precipitates. Electron microscopy characterization revealed that the sizes of the precipitates range from nano (<300 nm), sub-micron (300~800 nm) to micron (>1 μm). The bulk HEA exhibits excellent mechanical properties, of which the compressive yield strength, fracture strength, and plasticity at room temperature can reach 1508 MPa, 3106 MPa and 30.4 %, respectively, which are much higher than that of most HEAs prepared by Powder Metallurgy reported in the literatures, suggesting that the HEA developed is highly promising for engineering applications. The excellent mechanical properties of the bulk HEA can be attributed to that the multi-scale precipitates are fully coherent with the matrix, which could reduce the misfit strain at the interface, and relieve the stress concentration during deformation. 相似文献