The present paper is devoted to investigating the effects of various Ni-P contents on microstructure and related mechanical behavior of Fe-x(Ni+P)-1Cu alloys fabricated by semi-liquid phase sintering (SLPS) at 950 °C, with a special emphasis on strengthening effects of Cu nanoscale precipitates. Uniaxial compression testing and scanning electron microscope (SEM) were performed to correlate the microstructure with compression properties. Transmission electron microscope (TEM) studies were conducted to characterizing the ultrastructure of Fe-Ni-P-Cu alloy and accurately elucidating the strengthening effect of Cu nanoprecipitates. Experimental results show that the optimal Vickers hardness (465.4HV_0.1), ultimate compressive strength (1920 MPa) and yield strength (1223 MPa) would be available provided that alloys contain appropriate amount of Ni-P (around 25.3 wt%). But excess Ni-P (> 28.5 wt%) and resulting coarse phosphide phase at grain boundaries had a detrimental effect on the ductility (21.1%) of Fe-Ni-P-Cu alloy. A quantitative expression had been proposed to elaborate the relationship between yield strength, porosity and component content of as-prepared alloys. It was confirmed that, due to a high level of Ni content, the ultra-fine and dense Cu precipitates obtained could strongly strengthen Fe-Ni-P-Cu alloys even they were air-cooled rapidly. The observed yield strength increment contributed by Cu precipitates coincided with theoretical arithmetic.

本文致力于研究各种Ni-P含量对950°C半液相烧结（SLPS）制备的Fe-x（Ni + P）-1Cu合金的显微组织和相关力学行为的影响。特别强调铜纳米级沉淀物的强化作用。进行了单轴压缩测试和扫描电子显微镜（SEM），以将微观结构与压缩特性相关联。进行透射电子显微镜（TEM）研究以表征Fe-Ni-P-Cu合金的超微结构，并准确阐明Cu纳米沉淀的强化作用。实验结果表明，最佳的维氏硬度（465.4HV _0.1），极限抗压强度（1920 MPa）和屈服强度（1223 MPa）将可用，前提是合金含有适量的Ni-P（约25.3 wt％）。但是过量的Ni-P（> 28.5 wt％）和在晶界处产生的粗磷化物相对Fe-Ni-P-Cu合金的延展性（21.1％）有不利影响。已经提出了定量表达以详细说明所制备合金的屈服强度，孔隙率和组分含量之间的关系。可以肯定的是，由于镍含量高，所得到的超细致密的Cu析出物即使快速风冷也能强固Fe-Ni-P-Cu合金。观察到的由铜沉淀物引起的屈服强度增加与理论算术一致。