热处理对快速凝固ZK60镁合金薄带组织和硬度的影响

采用单辊甩带法制备了ZK60镁合金薄带,研究了不同条件热处理薄带的组织和显微硬度。结果表明,薄带由晶粒尺寸8μm的等轴α-Mg、球状β′2相和少量杆状β′1相组成;热处理温度300℃时,晶粒无长大;温度300℃时,晶粒显著长大。原始薄带显微硬度约为50HV,300℃×2h热处理后显微硬度值最大约为80HV;β′1和β′2相的弥散强化作用是薄带硬度提高的内在原因。

Effect of heat treatment on microstructure and microhardness of rapidly solidified ZK60 magnesium ribbons

The rapidly solidified(RS)ZK60 magnesium alloy ribbons were prepared by a single roller apparatus.Microstructure and microhardness of the ribbons with and without heat treatment were investigated by menas of optical microscope,TEM,XRD and microhardness test.The results show that the ribbons are composed of equiaxed α-Mg matrix with grain size 8 μm,spherical β'2 and a few rods β'1 phases.No growth of the α-Mg matrix grains is observed for the RS ZK60 alloy after annealing at temperature below 300 ℃.However,the grains grow significantly after annealing at temperatures higher than 300 ℃.The average microhardness of the RS ribbons of ZK60 alloy is about SO HV.Microhardness of the annealed RS ribbons increases firstly to a maximum value of 80 HV at 300 ℃ for 2 h and then decreases with increasing annealing temperature or prolonging annealing time at 300 ℃.The TEM observation suggests show that β'1 and β'2 phases are considered to be the main strengthening phases.