热处理对冷喷涂Al-Ni沉积体组织和力学性能的影响

Microstructure and Mechanical Properties of Al-Ni Deposits with Cold Spraying by Heat Treatment

Al-Ni金属间化合物具有高熔点、高蠕变强度、低密度、耐腐蚀和抗氧化等优良性能。本研究预先采用冷喷涂工艺制备Al-50%Ni沉积体,后将沉积体在450、500和550℃氩气环境中保温8 h进行热处理,探讨热处理对冷喷涂Al-50%Ni复合沉积体的显微组织、相成分、硬度和耐磨损性能的影响。结果表明:与喷涂态的Al-50%Ni沉积体相比,随着热处理温度的升高,沉积体中Al_(3)Ni、Al_(3)Ni_(2)相的含量逐渐增加,经550℃热处理后,显微组织基本转变为金属间化合物。同时,因Al、Ni在沉积体中扩散系数不相同,导致柯肯达尔效应出现,沉积体中孔隙率随温度升高逐渐增加。喷涂态Al-50%Ni沉积体的平均显微硬度为HV_(0.2)76.0,经450℃热处理后,沉积体形变强化效果消除,平均显微硬度为HV_(0.2)46.2,随着热处理温度升高,金属间化合物含量增加,沉积体的平均显微硬度在500℃时为HV_(0.2)98.6,550℃时为HV_(0.2)376。同时,热处理态Al-50%Ni沉积体的质量磨损均比冷喷涂态小;且随着热处理温度的升高,沉积体抗磨损性能逐渐提高。

Al-Ni intermetallic compounds have excellent properties such as high melting point,high creep strength,low density,good corrosion resistance and oxidation resistance.In this study,Al-50%Ni deposits were prepared by cold spraying in advance and then heat treated in argon gas at 450,500 and 550℃for 8 h,respectively.The influence of heat treatment on microstructure,phase composition,hardness and wear property of Al-50%Ni composite was discussed.The results showed that the content of Al3 Ni and Al3 Ni2 phases increased gradually with the increase of heat treatment temperature compared with the Al-50%Ni deposit in the assprayed state.After heat treatment at 550℃,the microstructure was basically transformed into intermetallic compounds.At the same time,the different diffusion coefficients of Al and Ni in the system lead to the emergence of the Kirkendall effect,and the porosity in the deposited body gradually increased with the rise of temperature.The average microhardness of Al-50%Ni deposit was HV_(0.2)76.0.After heat treatment at 450℃,the deformation strengthening effect of the deposit was eliminated,and the average microhardness was HV_(0.2)46.2.As the heat treatment temperature increased,the content of intermetallic compounds increased,and the average microhardness of the deposit was HV_(0.2)98.6 at 500℃and HV_(0.2)376 at 550℃.At the same time,the mass abrasion of Al-50%Ni deposit in heat treatment state was lower than that in the as-sprayed state,and the wear resistance of the deposits gradually rose with the increase of the heat treatment temperature.