Studies On Preparation And Mechanical Properties Of Y₂O₃/ Carbon Nanotubes/ Nickle Matrix Composite

Ni-base superalloys are important alloys for high-temperature materials used in gas turbines.Most of the nickel-base superalloys were developed on the basis of the Cr20-Ni alloy.Theγ'-phase depositions precipitated through aging treatment could improve the heat resistance of superalloys at middle temperature.It points out an new research field on Ni-base superalloys as Oxide Dispersion Strengthened(ODS) nickel-base matrix composites rised.The ODS nickel-base composite which were made by powder-metallurgy would have a very good development prospects.The Y₂O₃ nickel-base composites were made by powder-metallurgy using Cr20-Ni alloys as matrix.We studied the effects ofγ'-phase precipitated through aging treatment on the strengthened nickel-base composites.We studied the effects of Y₂O₃ addition in nickel-base composites.The high temperature performance of theγ'-Y₂O₃ combined effects on the composites were simulated according to Larson—Miller parameter equation.And we also studied the performance of the carbon nanotubes composites at the same time.The experiments show:1.Theγ'-phase depositions precipitated through aging treatment at 760℃for 24 hours could improve the heat resistance of composites at room temperature.For example,the tensile strength of the NiCr-6.0%Al aged is by 26%higher than 20CrNi alloy,their hardness is by 118%higher than 20CrNi alloy at the same time.2.The experiment suggested that Y₂O₃ composites containing 0.8%weight fraction of Y₂O₃ showed the best mechanical performance at room temperature,the hardness of the Y₂O₃ composite unaged is by 29%higher than NiCr-6.0%Al alloy,and is by 82%higher after aging.3.The hardness of nickel-base superalloys decreased rapidly and the Y₂O₃/NiCrAl composites decreased at the high temperature.When the heat simulation parameter was 31825,the hardness of NiCr-6.0%Al superalloys was only 183HV after high temperature treatment,while it was 345HV at room temperature.The hardness decreased by 47%.And the hardness of 0.8%Y₂O₃/NiCr-6.0%Al composite at high temperature was only by 25% lower than the hardness at room temperature.The test results of heat simulation are well agreed to Larson—Miller parameter equation.It shows that Larson—Miller parameters equation is accurate and applicable for the simulation of the performance of these composite materials at high temperature.4.When the volume fraction of carbon nanotubes is 15%,carbon nanotubes nickel-base composite has the best tensile strength and hardness.The addition of carbon nanotubes could obviously influence the saturation magnetization and coercivity of Nickel-base materials.