Study On The Preparation Of Cu-Cr-Zr Alloy Powder By Mechanical Alloying And Its Material Properties

Cu-Cr-Zr alloy is a new type of function material,has excellent and comprehensive performance.It bears excellent properties such as electrical conductivity,thermal conductivity and high strength.This kind of material is widely used in electric power,electrical equipment and aircraft industries.At present,the main difficulty in preparing Cu-Cr-Zr alloy is that Cr and Zr have low solid solubility in Cu and are liable to produce solute segregation.In order to deal with these problems above,Cu-Cr-Zr alloy were prepared by mechanical alloying.We took use of the high-energy output of the high energy ball milling to prepare Cu-Cr-Zr alloy powders with high Cr and Zr solid solubility and uniform composition.Moreover,the vacuum hot-press sintering process was used to synthesize the powder,and the impact of the alloy composition on the alloy performance was studied.(1)The effect of milling parameters on the properties of Cu-10 wt%Cr-10 wt%Zr alloy powders was investigated by single factor method.The effects of milling time,rotational speed,milling additives content,ball-to-powder weight ratio and milling media size on the alloying time and microstructure of Cu-10 wt%Cr-10 wt%Zr powder were analyzed.Through SEM observation of the powder and XRD analysis of its composition,we found that when the rotational speed is 1100/1300 rpm,the content of the milling additives is 1.5 wt%,the ball-to-powder weight ratio is 10:1 and bearing steel ball is 4 mm,the minimum time require for alloying Cu-10 wt%Cr-10 wt%Zr powder is 30 h.(2)The influence of the change of Cr content(0.5 wt%-10 wt%)in Cu-Cr alloy on mechanical and electrical properties was studied.XRD,SEM,mechanical stretch and conductivity tests were performed on the alloy to characterize its composition and conduct a performance analysis.When the Cr content is 5 wt%,the Cu-5 wt% Cr powder was alloyed at 20 h after milling.The maximum tensile strength of the alloy is 721.51 MPa,and increased by 262.56% compared to pure copper.The conductivity is 59.30% IACS and the addition of Cr was determined to be 5 wt%.(3)The effect of the change of the Zr content(1 wt%-15 wt%)in the Cu-5 wt%Cr-Zr alloy on the mechanical and electrical properties of the alloy was explored.The composition mechanical and electrical properties of the alloy were tested by XRD analysis,SEM observation,a mechanical tester,and an electrical conductivity meter.When the content of Zr is 8 wt%,the time require for powder alloying is 25 h.The maximum tensile strength of the alloy is 829.15 MPa,which is 316.65% higher than that of pure copper,and the electrical conductivity is 43.70% IACS.Therefore,we chose to add 8 wt% Zr to obtain Cu-5 wt% Cr-8 wt% Zr alloy.(4)The strengthening mechanism and microstructure of Cu-5 wt%Cr-8 wt%Zr alloy were investigated.The fracture morphology and microstructure of the alloy were characterized by SEM,metallography and TEM.The strengthening mechanism of the alloy is solution strengthening.By analyzing the fracture morphology of the alloy,we discovered that the number of dimples in the fracture surface of the Cu-5 wt% Cr-Zr alloy increased with the increase of Zr content(1 wt% to 15 wt%),and the dimples became larger and deeper.The alloy gradually transforms from brittle fracture to ductile fracture.The failure mode is the tearing in the matrix and the fracture of the solid solution particles of the alloy.