预退火温度对半固态铜合金坯料组织演变和力学性能的影响

Influence of pre-annealing temperature on microstructure evolution and mechanical properties of semi-solid copper alloy billet

摘要:

将铸态CuSn10P1铜合金先预退火处理,随后采用冷轧等温处理应变诱导熔化激活法(CRITSIMA)制备成半固态坯料。采用金相显微镜、配置能谱仪的扫描电子显微镜、X射线衍射仪、电子探针和布氏硬度计,研究预退火温度对半固态铜合金坯料的组织演变及力学性能的影响。结果表明：随着预退火温度升高,半固态铜合金坯料的平均晶粒尺寸增加,晶粒形状因子和液相率均降低；随着预退火温度升高,α-Cu相中固溶更多的Sn元素,减弱了Sn元素偏析,晶间脆硬相δ相含量减少,布氏硬度逐渐减小。在半固态铜合金坯料中检测到新相Cu_13.7Sn的存在,这与晶间Sn元素的高度偏析有关。600 ℃预退火2 h制备的半固态铜合金坯料显微组织晶粒均匀细小,力学性能较好,其平均晶粒尺寸为68.34μm、晶粒形状因子为0.78、α-Cu基体中Sn元素固溶度为4.21wt%,布氏硬度为128 HBW。

Abstract:

The as-cast CuSn10P1 copper alloy was pre-annealed and then prepared into semi-solid billets by cold rolling isothermal treatment strain-induced melting activation method (CRITSIMA). Using metallographic microscope, scanning electron microscope (SEM) equipped with energy dispersive spectrometer, X-ray diffractometer, electron probe and Brinell hardness tester, the effects of pre-annealing temperature on the microstructure evolution and mechanical properties of semi-solid copper alloy billets were studied. The results show that with the increase of the pre-annealing temperature, the average grain size of the semi-solid copper alloy billet increases, and the shape factor and liquid phase rate decrease; with the increase of the pre-annealing temperature, the solid solution in the α-Cu phase increases with more Sn element, the segregation of Sn element is weakened, the content of intergranular brittle and hard phase δ phase decreases, and the Brinell hardness gradually decreases. The existence of a new phase Cu_13.7Sn was detected in the semi-solid copper alloy billet, which is related to the high segregation of the intergranular Sn element. The semi-solid copper alloy billet prepared by pre-annealing at 600 ℃ for 2 h has fine and uniform microstructure and good mechanical properties. The average grain size is 68.34 μm, the shape factor is 0.78, the solid solubility of Sn in α-Cu matrix is 4.21wt%, and the Brinell hardness is 128 HBW.