The Effects Of Fe?Ti On Microstructure And Properties Of Laves Phase TaCr₂ Alloy

Laves phase TaCr₂ intermetallic compound has higher melting point,moderate density,excellent high temperature oxidation resistance,high temperature strength and good creep resistance.The Laves phase TaCr₂ is expected to become a new type of high temperature structural material to replace nickel based superalloys,and become a new type of high temperature candidate structural material for aircraft engines.However,its room-temperature brittleness,it is very difficult to be processed and formed,which seriously hinders its practical application.In this paper,alloy samples were prepared by mechanical alloying?MA 25 h,speed 400r/min and ball material ratio 13:1?and hot pressing?1350?�1h?.The effects of Fe and Ti on microstructure and mechanical properties of Laves phase TaCr₂ were investigated along with the research of TaCr FeTi-X high entropy alloy by means of metallographic microscope,X-ray diffraction spectrum,scanning electron microscope and energy spectrum analysis.The results show that the average grain size of the mixed powders?Ta Cr₂,Ta Cr₂-10 Fe,Ta Cr₂-20 Fe,Ta Cr₂-30 Fe,Ta Cr₂-35Fe?reached nanometer grade?3.17³4.17nm?after 25-hour mechanical alloying.No intermetallic compounds can be synthesized by the blended Ta,Cr and Fe powders during the ball-milling time of25 h.The highly dense alloys were obtained from the ball-milled blended powders by the hot-pressing process with a sintering temperature of 1350? and a sintering time of 1 hour.The density of alloy increases with the increase of Fe content.When the content of Fe is above 30 at.%,the density of alloy is more than 99%,which is close to full density.The TaCr₂ alloy with an addition of Fe could inhibit the generation of Laves phase TaCr₂ with a C15 structure,and the alloying element Fe preferentially occupies the Cr site in the Laves phase TaCr₂.TaCr₂-35 Fe alloy has relatively better room temperature mechanical properties in the five components of TaCr₂-Fe alloy,which has 7.13 GPa of vivtorinox hardness,5.448MPa�m1/2 of fracture toughness and 1719 MPa of compressive strength.The Fe element has good toughening effect on TaCr₂ alloy.The average grain size of the mixed powders?TaCr₂,TaCr₂-10 Ti,TaCr₂-20 Ti,TaCr₂-30 Ti,TaCr₂-35Ti?reached nanometer grade?34.17⁶6.36nm?after 25-hour mechanical alloying.No intermetallic compounds can be synthesized by the blendedTa,Cr and Ti powders during the ball-milling time of 25 h.The highly dense alloys were obtained from the ball-milled blended powders by the hot-pressing process with a sintering temperature of 1350? and a sintering time of 1 hour.The density of alloy increases with the increase of Ti content.The density of TaCr₂-30 Ti ?TaCr₂-35 Ti alloy is more than 99%,which is close to full density.The TaCr₂ alloy with an addition of Ti could inhibit the generation of Laves phase TaCr₂ with a C14 structure,and the alloying element Ti preferentially occupies the Ta site in the Laves phase TaCr₂.TaCr₂-30 Ti alloy has relatively good room temperature mechanical properties in the five component TaCr₂-Ti alloy,which has 9.76 GPa of vivtorinox hardness,4.663MPa�m1/2 of fracture toughness and 1518 MPa of compressive strength.The Ti element has good toughening effect on TaCr₂ alloy,but the toughening effect is less than the toughening effect of Fe.The average grain size of the mixed powders?TaCr FeTi,TaCr FeTiNi,TaCr FeTiMo,TaCrFeTiNb?reached nanometer grade?18.53³3.99nm?by 25 h after ball milling.No intermetallic compounds can be synthesized by the blended TaCr FeTi-X powders during the ball-milling time of 25 h.High density alloy can be prepared by hot pressing at 1350? for 1h.The densities of the four alloys are greater than 99% which is close to full density.The phase composition of the four alloys is not a single and simple solid solution phase but mainly being made up of intermetallic compounds.TaCrFeTiNb alloy has relatively good room temperature mechanical properties in the four component alloys,which has 8.72 GPa of vivtorinox hardness,6.47MPa�m1/2 of fracture toughness and 1562.9MPa of compressive strength.