【摘要】 采用粉末冶金法,通过添加W、Zr、Th制备铱合金,研究微量元素对高温铱合金的强化作用。结果表明,当Zr的加入量大于4wt%后与Ir形成了Ir/Ir3Zr共格结构,起到共格强化作用;抗压强度增加,但材料变脆,晶粒粗大;W的加入起到了固溶强化作用,改变了材料晶体结构,细化了晶粒,提高了铱合金的强度。同时发现少量W的加入,降低了铱合金的烧结温度,提高了烧结密度,相对密度可达95%以上,达到了热变形加工的密度要求,经热变形加工(锻造、轧制)的铱合金板材,合金的高温力学性能获得了明显的改善;10-6级的Th加入到Ir-Zr,Ir-W中,起到了晶界弥散强化作用,明显的细化了晶粒,提高了合金晶界强度,显著改变了合金的微观显微结构,断面从沿晶断裂方式转为穿晶断裂,提高了材料的高温力学性能,增强了材料的延展性。采用俄歇能谱分析Ir-W-Th合金晶界,发现Th在铱的晶界上富集,明显抑制了铱的晶粒长大,提升了铱的晶界结合强度,大幅度提高了铱的结合强度,起到较好的晶界弥散强化作用。在1400℃下,Ir-W-Th合金的拉伸强度达到140 MPa,伸长率达29%。更多还原

【Abstract】 Iridium alloy was prepared by adding minor W,Zr and Th using in powder metallurgy method.Strengthening effect of trace element on the Ir alloy was studied.The results indicate that Zr and Ir forms Ir/Ir3Zr coherent structure when the adding amount of Zr over 4wt%.The Ir/Ir3Zr phase can strengthen the crystal structure,lead to compression strength increasing,but the grains growing and the structure embrittling.Adding W can refine the crystal structure and restrict the growth of grains,which lead to the improved strength.It is also found that adding minor W can reduce the sintering temperature and improve sintered density(the relative density can reach >95%).The high density can satisfy the demand of hot deformation.Ir alloy plate through hot deformation processing has improved high-temperature mechanical properties.Adding minor Th with 10-6 level can strengthen the crystal boundary and restrict the growth of grains,which lead to improved mechanical properties and ductility.AES analysis reveals that Th enriches in the grain boundary of Ir-W-Th alloy and restrict the grain growth of Ir alloy,which brings with improved bonding strength of grain boundary of Ir alloy.The tension strength and elongation of Ir-W-Th alloy at 1400 ℃ can reach 140 MPa and 29%,respectively.更多还原