半固态铜合金反挤压成形组织演变及偏析行为

Microstructure evolution and segregation behavior of copper alloy during semi-solid backward extrusion

采用轧制−重熔应变诱导熔化激活法(SIMA)制备半固态浆料并进行反挤压成形制备不同成形阶段的铜合金轴套零件,研究铜合金半固态反挤压成形过程中的组织演变和偏析行为。结果表明:半固态ZCuSn10P1铜合金组织主要由α-Cu相、Cu_(41)Sn_(11)(δ)相、Cu_(3)P相和Cu_(13.7)Sn(β′)相组成,半固态反挤压过程中浆料由型腔底部向端部充型,产生明显的固−液偏析;随着半固态ZCuSn10P1铜合金成形的进行,固−液偏析倾向减小,组织缺陷减少,当完全成形时组织中无明显缺陷,晶粒圆整度较好且分布均匀;半固态反挤压成形ZCuSn10P1铜合金组织中微观元素偏析倾向严重,Sn、P元素在晶间和晶内液岛富集,而在α-Cu基体中含量较少。随着半固态铜合金成形的进行,半固态ZCuSn10P1铜合金中Sn元素偏析现象加剧,完全成形时,其偏析程度有所减小,但相同类型区域元素的均匀性较差。

The semi-solid slurry was prepared by rolling remelting strain induced melting activation method(SIMA),and the copper alloy shaft sleeve parts at different forming stages were prepared by back extrusion.The microstructure evolution and segregation behavior of copper alloy during semi-solid back extrusion were studied.The results show that the phase structure of semi-solid ZCuSn10P1 copper alloy is mainly composed ofα-Cu phase,Cu_(41)Sn_(11)(δ)phase,Cu_(3)P phase and Cu_(13.7)Sn(β′)phase.During the semi-solid extrusion process,the slurry is filled from the bottom of the cavity to the end,and obvious solid-liquid segregation occurs during the forming process.The tendency of solid-liquid segregation and structural defects decrease with the semi-solid ZCuSn10P1 copper alloy forming.When the semi-solid extrusion is fully formed,there is no obvious defects in the structure,and the grain roundness is high and the grain distribution is uniform.The segregation of micro elements is serious in the microstructure of semi-solid extruded copper alloy,and Sn and P elements are enriched in intergranular and intragranular liquid islands,while the content of Sn and P elements in the matrix is less.With the semi-solid ZCuSn10P1 copper alloy forming,the segregation of Sn element in semi-solid copper alloy intensifies.The segregation degree decreases when the semi-solid ZCuSn10P1 copper alloy is fully formed,but the element homogeneity in the same type of area is poor.