The 800℃ isothermal section in the Al-Zn-Zr system was investigated using the equilibrated alloy method and the solid/liquid diffusion couple approach by means of scanning electron microscopy equipped with energy dis...The 800℃ isothermal section in the Al-Zn-Zr system was investigated using the equilibrated alloy method and the solid/liquid diffusion couple approach by means of scanning electron microscopy equipped with energy dispersive spectroscopy, X-ray powder diffraction and electron probe microanalysis. Thirteen three-phase regions are experimentally confirmed in the ternary system. A ternary compound Zn50Al25Zr25 named as T phase exists stably in the 800℃ isothermal section. Its composition range varies widely (16.84-55.1 at.% Zn, 18.02-56.3 at.% Al and 26.0-28.53 at.% Zr), and it can be in equilibrium with all the binary compounds. The maximum solubilities of Zn in Zr3Al, Zr2Al, Zr3Al2, Zr4Al3, ZrAl, Zr2Al3, ZrAl2 and ZrAl3 are 7.5, 0.84, 0.33, 0.89, 0.91, 1.12, 0.64 and 3.8 at.%, respectively. The maximum solubilities of Al in Zn3Zr, Zn2Zr and ZnZr are 1.6, 1.3 and 13.6 at.%, respectively.展开更多
Al-high Si alloys were designed by the addition of Cu or Mg alloying elements to improve the mechanical properties. It is found that the addition of 1 wt.% Cu or 1 wt.% Mg as strengthening elements significantly impro...Al-high Si alloys were designed by the addition of Cu or Mg alloying elements to improve the mechanical properties. It is found that the addition of 1 wt.% Cu or 1 wt.% Mg as strengthening elements significantly improves the tensile strength by 27.2% and 24.5%, respectively. This phenomenon is attributed to the formation of uniformly dispersed fine particles(Al2Cu and Mg2Si secondary phases) in the Al matrix during hot press sintering of the rapidly solidified(gas atomization) powder. The thermal conductivity of the Al-50 Si alloys is reduced with the addition of Cu or Mg, by only 7.3% and 6.8%, respectively. Therefore, the strength of the Al-50 Si alloys is enhanced while maintaining their excellent thermo-physical properties by adding 1% Cu(Mg).展开更多
The microstructive and compressive properties of Ti50Al48,Mn2 and Ti50Al48Cr2 alloys are studied in this paper. Existence of x-x+y transformation in TiAl alloys is confirmed by metallographic examination, the transfor...The microstructive and compressive properties of Ti50Al48,Mn2 and Ti50Al48Cr2 alloys are studied in this paper. Existence of x-x+y transformation in TiAl alloys is confirmed by metallographic examination, the transformation temperatures of Ti5()Al48 Mn2 and Ti50Al48Cr2 are 1375 and 1373 C , respectively. After treating within x+y phase field, the microstructure of alloys consists of lamellar zones (I) and bulk rp. The volume ratio of L /rp increases with increasing solution treatment temperature. The third alloying elements of Mn and Cr distribute perferentially over x phase at solution treatment temperatures and result in that x2 and r lamellae become thicker. The yield strength of Ti50Al48Mn2 and Ti50Al48Cr2 alloys decreases and the compressibility increases with increasing rp volume fraction.展开更多
In the present investigation, Ni_（50）Ti_（25）Al_（25）（at.%） mechanically alloyed powder is deposited on carbon steel substrate.Before the coating process, the substrate is heated to temperature ranging from room...In the present investigation, Ni_（50）Ti_（25）Al_（25）（at.%） mechanically alloyed powder is deposited on carbon steel substrate.Before the coating process, the substrate is heated to temperature ranging from room temperature to 400℃. The microstructure, porosity, microhardness, adhesion strength, and corrosion behavior of the coating are investigated at different substrate temperatures. Results show that coating porosity is lower on high temperature surface. Microhardness and adhesion strength of the deposition layer on the substrate without preheating have lower values than with preheating. The polarization test result shows that corrosion performance of the coating is dependent on micro cracks and porosities and the increasing of substrate temperature can improve the quality of coating and corrosion performance.展开更多
基金Projects(51771160,51471140)supported by the National Natural Science Foundation of China
文摘The 800℃ isothermal section in the Al-Zn-Zr system was investigated using the equilibrated alloy method and the solid/liquid diffusion couple approach by means of scanning electron microscopy equipped with energy dispersive spectroscopy, X-ray powder diffraction and electron probe microanalysis. Thirteen three-phase regions are experimentally confirmed in the ternary system. A ternary compound Zn50Al25Zr25 named as T phase exists stably in the 800℃ isothermal section. Its composition range varies widely (16.84-55.1 at.% Zn, 18.02-56.3 at.% Al and 26.0-28.53 at.% Zr), and it can be in equilibrium with all the binary compounds. The maximum solubilities of Zn in Zr3Al, Zr2Al, Zr3Al2, Zr4Al3, ZrAl, Zr2Al3, ZrAl2 and ZrAl3 are 7.5, 0.84, 0.33, 0.89, 0.91, 1.12, 0.64 and 3.8 at.%, respectively. The maximum solubilities of Al in Zn3Zr, Zn2Zr and ZnZr are 1.6, 1.3 and 13.6 at.%, respectively.
文摘Al-high Si alloys were designed by the addition of Cu or Mg alloying elements to improve the mechanical properties. It is found that the addition of 1 wt.% Cu or 1 wt.% Mg as strengthening elements significantly improves the tensile strength by 27.2% and 24.5%, respectively. This phenomenon is attributed to the formation of uniformly dispersed fine particles(Al2Cu and Mg2Si secondary phases) in the Al matrix during hot press sintering of the rapidly solidified(gas atomization) powder. The thermal conductivity of the Al-50 Si alloys is reduced with the addition of Cu or Mg, by only 7.3% and 6.8%, respectively. Therefore, the strength of the Al-50 Si alloys is enhanced while maintaining their excellent thermo-physical properties by adding 1% Cu(Mg).
文摘The microstructive and compressive properties of Ti50Al48,Mn2 and Ti50Al48Cr2 alloys are studied in this paper. Existence of x-x+y transformation in TiAl alloys is confirmed by metallographic examination, the transformation temperatures of Ti5()Al48 Mn2 and Ti50Al48Cr2 are 1375 and 1373 C , respectively. After treating within x+y phase field, the microstructure of alloys consists of lamellar zones (I) and bulk rp. The volume ratio of L /rp increases with increasing solution treatment temperature. The third alloying elements of Mn and Cr distribute perferentially over x phase at solution treatment temperatures and result in that x2 and r lamellae become thicker. The yield strength of Ti50Al48Mn2 and Ti50Al48Cr2 alloys decreases and the compressibility increases with increasing rp volume fraction.
文摘In the present investigation, Ni_（50）Ti_（25）Al_（25）（at.%） mechanically alloyed powder is deposited on carbon steel substrate.Before the coating process, the substrate is heated to temperature ranging from room temperature to 400℃. The microstructure, porosity, microhardness, adhesion strength, and corrosion behavior of the coating are investigated at different substrate temperatures. Results show that coating porosity is lower on high temperature surface. Microhardness and adhesion strength of the deposition layer on the substrate without preheating have lower values than with preheating. The polarization test result shows that corrosion performance of the coating is dependent on micro cracks and porosities and the increasing of substrate temperature can improve the quality of coating and corrosion performance.
