为提高热轧态0Cr21A16合金板材的组织均匀性和塑性,以改善其高温性能及冷加工特性,分析研究了不同温度的热处理试验及组织性能。采用光学显微镜、X射线衍射仪、Gleeble高温热拉伸实验、扫描电镜和纳米压痕仪等研究了热处理前后0Cr21Al6...为提高热轧态0Cr21A16合金板材的组织均匀性和塑性,以改善其高温性能及冷加工特性,分析研究了不同温度的热处理试验及组织性能。采用光学显微镜、X射线衍射仪、Gleeble高温热拉伸实验、扫描电镜和纳米压痕仪等研究了热处理前后0Cr21Al6合金板材的显微组织和力学性能。结果表明,通过热处理的方式改善0Cr21Al6合金板材的组织均匀性,在960℃保温6 min 40 s后快速冷却,晶粒平均尺寸为42μm,整体的晶粒尺寸相对于940、980、1000、1020℃热处理后较为均匀、细小,硬度和塑性达到最佳匹配,断裂韧度KIC在960℃处理下达到最佳,拥有最佳的综合性能,可有效避免生产过程中材料的脆性断裂问题。另外Gleeble实验显示1000℃以上的热处理温度不再适合于热加工。展开更多
The improvements of microstructures and properties of a high strength aluminum cast alloy were studied. The effects of rare earth elements on the microstructures and mechanical properties of the high strength cast all...The improvements of microstructures and properties of a high strength aluminum cast alloy were studied. The effects of rare earth elements on the microstructures and mechanical properties of the high strength cast alloy Al-Cu-Mg-Si were investigated. The result shows that the addition of rare earth elements can change the microstructures in refining the grain size of the alloy and making the needle-like and laminar eutectic Si to a granular Si. With the increase of the rare earth, the tensile strength and elongation of the alloy increase first and then fall down. The mechanical properties of the alloy will reach the highest value when the content of rare earth elements is about 0.7%.展开更多
The site occupancy behavior of ternary alloying elements inγ'-Ni3Al(a key strengthening phase of commercial Ni-based single-crystal superalloys)can change with temperature and alloy composition owing to the effec...The site occupancy behavior of ternary alloying elements inγ'-Ni3Al(a key strengthening phase of commercial Ni-based single-crystal superalloys)can change with temperature and alloy composition owing to the effect of entropy.Using a total-energy method based on density functional theory,the dependence of tensile and shear behaviors on the site preference of alloying elements inγ'-Ni3Al were investigated in detail.Our results demonstrate that Fe,Ru,and Ir can significantly improve the ideal tensile and shear strength of theγ'phase when occupying the Al site,with Ru resulting in the strongest enhancement.In contrast,elements with fully filled d orbitals(i.e.,Cu,Zn,Ag,and Cd)are expected to reduce the ideal tensile and shear strength.The calculated stress-strain relationships of Ni3Al alloys indicate that none of the alloying elements can simultaneously increase the ideal strength of theγ'phase for both Ni1-site and Ni2-site substitutions.In addition,the charge redistribution and the bond length of the alloying elements and host atoms during the tensile and shear processes are analyzed to unveil the underlying electronic mechanisms.展开更多
The oxidation behaviors of two kinds of low segregation Ht-Cr-Al based superalloys have been studied between 1000-1100℃, and compared with that of general Mt-Cr-Al based superalloys. The results indicated that the si...The oxidation behaviors of two kinds of low segregation Ht-Cr-Al based superalloys have been studied between 1000-1100℃, and compared with that of general Mt-Cr-Al based superalloys. The results indicated that the simultaneous additions of 0.1 wt% S and 0. 1 wt% Zr to low segregation alloys increase the oxidation rate of Al2O3-forming alloy and improve the scale adherence. The addition of 0.1 wt% Zr can ,minimize the negative effects of S on the adherence of Al2O3 scale. Low amounts of S(≤50 ppm wt) have no obviously negative effects on the adherence of Cr2O3 scale formed on one of the low segregation superalloys.展开更多
It was shown by TEM and X-ray analysis that there are four types of grains of the main Ni3Al phase in the structure of the intermetallic obtained by the self-propagation high temperature method (SHS). Every type of gr...It was shown by TEM and X-ray analysis that there are four types of grains of the main Ni3Al phase in the structure of the intermetallic obtained by the self-propagation high temperature method (SHS). Every type of grains has its own domain and dislocation structure. There are mono- and polydomains with and without dislocations. The grains of the main phase of monoand polydomains without dislocations and polydomains with dislocations were formed by diffusion in the solid phase. In these conditions NiAl3 phase is located on the grain boundary of the main phase. The Ni2Al3 phase is located at the triple joints of the main phase.展开更多
The microstructures of Ti-14Al-21Nb and Ti-14Al-20Nb-2Mo-3.2V(wt%) alloys have been investikated by transmission electron microscopy(TEM).The phase constitution and the orientation relationship between α2and βwere i...The microstructures of Ti-14Al-21Nb and Ti-14Al-20Nb-2Mo-3.2V(wt%) alloys have been investikated by transmission electron microscopy(TEM).The phase constitution and the orientation relationship between α2and βwere identified by means of the selected area diffraction and the micro-diffraction techniques.Results show that,compared to Ti-14Al-21Nb,the alloying elements Mo and V can greatly increase the fraction of β phase and improve significantly the microstructures of Ti-14Al-20Nb-2Mo-3.2V.The ordered B2 structure is also evident in the residual βgrains of the latter alloy.展开更多
文摘为提高热轧态0Cr21A16合金板材的组织均匀性和塑性,以改善其高温性能及冷加工特性,分析研究了不同温度的热处理试验及组织性能。采用光学显微镜、X射线衍射仪、Gleeble高温热拉伸实验、扫描电镜和纳米压痕仪等研究了热处理前后0Cr21Al6合金板材的显微组织和力学性能。结果表明,通过热处理的方式改善0Cr21Al6合金板材的组织均匀性,在960℃保温6 min 40 s后快速冷却,晶粒平均尺寸为42μm,整体的晶粒尺寸相对于940、980、1000、1020℃热处理后较为均匀、细小,硬度和塑性达到最佳匹配,断裂韧度KIC在960℃处理下达到最佳,拥有最佳的综合性能,可有效避免生产过程中材料的脆性断裂问题。另外Gleeble实验显示1000℃以上的热处理温度不再适合于热加工。
基金This work was financially supported by the Fund of BeijingJiaotong University(No.2004SZ006).
文摘The improvements of microstructures and properties of a high strength aluminum cast alloy were studied. The effects of rare earth elements on the microstructures and mechanical properties of the high strength cast alloy Al-Cu-Mg-Si were investigated. The result shows that the addition of rare earth elements can change the microstructures in refining the grain size of the alloy and making the needle-like and laminar eutectic Si to a granular Si. With the increase of the rare earth, the tensile strength and elongation of the alloy increase first and then fall down. The mechanical properties of the alloy will reach the highest value when the content of rare earth elements is about 0.7%.
基金Project supported by the National Natural Science Foundation of China(Grant No.11804057)the Natural Science Foundation of Guangdong Province,China(Grant No.2017B030306003)the National Key Research and Development Program of China(Grant No.2017YFB0701500).
文摘The site occupancy behavior of ternary alloying elements inγ'-Ni3Al(a key strengthening phase of commercial Ni-based single-crystal superalloys)can change with temperature and alloy composition owing to the effect of entropy.Using a total-energy method based on density functional theory,the dependence of tensile and shear behaviors on the site preference of alloying elements inγ'-Ni3Al were investigated in detail.Our results demonstrate that Fe,Ru,and Ir can significantly improve the ideal tensile and shear strength of theγ'phase when occupying the Al site,with Ru resulting in the strongest enhancement.In contrast,elements with fully filled d orbitals(i.e.,Cu,Zn,Ag,and Cd)are expected to reduce the ideal tensile and shear strength.The calculated stress-strain relationships of Ni3Al alloys indicate that none of the alloying elements can simultaneously increase the ideal strength of theγ'phase for both Ni1-site and Ni2-site substitutions.In addition,the charge redistribution and the bond length of the alloying elements and host atoms during the tensile and shear processes are analyzed to unveil the underlying electronic mechanisms.
文摘The oxidation behaviors of two kinds of low segregation Ht-Cr-Al based superalloys have been studied between 1000-1100℃, and compared with that of general Mt-Cr-Al based superalloys. The results indicated that the simultaneous additions of 0.1 wt% S and 0. 1 wt% Zr to low segregation alloys increase the oxidation rate of Al2O3-forming alloy and improve the scale adherence. The addition of 0.1 wt% Zr can ,minimize the negative effects of S on the adherence of Al2O3 scale. Low amounts of S(≤50 ppm wt) have no obviously negative effects on the adherence of Cr2O3 scale formed on one of the low segregation superalloys.
文摘It was shown by TEM and X-ray analysis that there are four types of grains of the main Ni3Al phase in the structure of the intermetallic obtained by the self-propagation high temperature method (SHS). Every type of grains has its own domain and dislocation structure. There are mono- and polydomains with and without dislocations. The grains of the main phase of monoand polydomains without dislocations and polydomains with dislocations were formed by diffusion in the solid phase. In these conditions NiAl3 phase is located on the grain boundary of the main phase. The Ni2Al3 phase is located at the triple joints of the main phase.
文摘The microstructures of Ti-14Al-21Nb and Ti-14Al-20Nb-2Mo-3.2V(wt%) alloys have been investikated by transmission electron microscopy(TEM).The phase constitution and the orientation relationship between α2and βwere identified by means of the selected area diffraction and the micro-diffraction techniques.Results show that,compared to Ti-14Al-21Nb,the alloying elements Mo and V can greatly increase the fraction of β phase and improve significantly the microstructures of Ti-14Al-20Nb-2Mo-3.2V.The ordered B2 structure is also evident in the residual βgrains of the latter alloy.
