添加球磨粉末对铁基高温合金锻态显微组织与力学性能的影响

Effect of additing mechanical alloyed powder on microstructure and mechanical properties of hot-forged iron-based alloys

采用SEM、能谱分析、XRD、密度和室温拉伸性能测定相结合的方法,研究添加球磨粉末对铁基高温合金锻态组织和力学性能的影响。结果表明:添加球磨粉末的混合粉末锻造合金的显微组织由几百纳米的细晶粒和几十微米的粗晶粒组成,具有明显晶粒尺寸双峰分布特征,其中细晶粒的形成提高了合金的界面能,有利于元素的扩散、成分均匀化和孔隙的消除。混合粉末锻造合金的抗拉强度与塑性均高于雾化粉末锻造合金,这是由于混合粉末锻造合金中少量纳米级第二相粒子钉扎晶界,可阻碍晶粒长大,使合金的强度与塑性分别达到888.9 MPa和18.32%。同时,混合粉末锻造合金中少量具有纳米尺寸的细晶粒有助于提高材料的强度和塑性。

The effect of the addition of mechanical alloyed powder on the microstructure and mechanical properties of hot-forged iron-based alloys was investigated by SEM,EDS,XRD,density measurements and tensile tests at room temperature.The results show that the microstructure of the as-forged alloy with mixed powder which consists of mechanical alloyed powder and gas-atomized powder has a bimodal grain size distribution.It is composed of two distinguishable kinds of grains-fine grains of hundreds of nanometers sized and coarse grains of tens of micrometers sized.Due to the higher interface energy of the fine grains,the formation of the nanometer-sized grains is beneficial to the elemental diffusion,homogeneity of components,and decrease of porosity.Both of the ultimate tensile strength and the plasticity of the as-annealed alloy with mixed powder are superior to the as-annealed alloy with gas-atomized powder,which is because that the nanometer-sized second phase particles in the as-annealed alloy with mixed powder can pin the grain boundary and inhabit the grain growth,the tensile strength and elongation of as-forged alloy with mixed powder are 888.9 MPa and 18.32%,respectively.Meanwhile,the fine grains of hundreds of nanometers sized in the as-annealed alloy with mixed powder can enhance both the ultimate tensile strength and the plasticity.