Cu-3.0Ni-0.75Si合金时效析出动力学分析

为研究Cu-3.0Ni-0.75Si合金时效过程中沉淀相的析出与长大规律,及其对合金硬度的影响,采用涡流电导仪和布氏硬度计分别测量合金的电导率和硬度,根据导电率与新相析出量之间的关系分析合金的时效析出动力学过程.结果表明,在350℃下时效,合金硬度随时效时间的延长,先升高后趋于平缓;在450℃、550℃下时效,合金硬度随时效时间的增加快速上升,到达峰值后缓慢下降;时效温度越高,合金硬度峰值越低,但硬度达到峰值所需的时间越短.温度一定,随时效时间的增加,合金电导率在时效初期快速升高,至峰值后趋于平缓.根据Cu-3.0Ni-0.75Si合金在450℃时效过程中电导率的变化,通过Avrami方程推导出相应的相变动力学方程及电导率方程分别为f=1-exp(-0.052 2t0.717 61)和σ=15.2+16.31-exp(-0.052 2t0.717 61)],采用相关系数检验法及F检验法对电导率方程的可信性进行检验,结果说明时效析出动力学方程和电导率方程具有一定的可靠性.对比由电导率经验方程得出的电导率理论值与测量得出的实验值,该理论值与实验值有良好的吻合度.

Study on dynamics of aging precipitation of Cu-3.0Ni-0.75Si alloy

The effects of aging temperature and aging time on microstructure evolution and properties of Cu-3.0Ni-0.75Si alloy were investigated by eddy current conductivity meter and Brinell hardness tester. The kinetics of the aging process is analyzed by studying the relationship between the electrical conductivity and the quantity of new phase. The results show that the hardness increases as the hold time increases, and then it flattens when the aging time increase under 350 ℃. The hardness increases rapidly with the increase of the hold time under 450 ℃ and 550 ℃, and it declines slowly after reaching the peak. When the aging temperature increases, the time to reach the peak value is shortened but the hardness drops down. The initial electrical conductivity increases rapidly during the aging process, then it flattens with the hold time increases under the aging temperature. The equation of the phase transformation kinetics and electrical conductivity equation of Cu-3.0Ni-0.75Si alloy aging at 450℃ is f= 1-exp(-0.052 2t0.717 61) andσ=15.2+16.31-exp (-0.052 2t0.717 61 ) ] , respectively . Those equation are deduced according to Avrami empirical formula andelectrical conductivity equation have a good dependability. The calculation values of electrical conductivity coincide well with the experiment results.