摘要
通过合金设计的方法分别制备了具有单相(γ-TiAl)组织的合金A、二相(γ-TiAl+α2-Ti3Al)层片组织的合金B和三相(γ-TiAl+α2-Ti3Al+Nb2Al)混合组织的合金C3种Ti-Al-Nb三元合金,通过XRD、EPMA以及SEM等手段确定了这3种合金的组织结构和分布形态,并对这3种合金进行了室温和1173K的拉伸试验。结果表明,合金的显微组织与其性能密切相关,室温下合金B的塑性变形能力好于另外两种合金,这主要是因为α2相的存在降低了合金平均晶粒尺寸,由γ和α2两相构成的层片组织结构以及大量的γ/α2相界面。温度升高可以显著改善合金B的塑性变形能力,合金B在1173K时的拉伸延性达到40.4%,并且断裂方式从室温时的穿晶脆性断裂向1173K时的韧性断裂方式转变,而合金A、C不管在室温还是1173K,都显示出穿晶脆性断裂方式。合金C在室温和高温都很脆,是由于Nb2Al相的出现,降低了(γ+α2)两相层片组织的连续程度。
Three types of Ti-Al-Nb ternary alloys were prepared by arc-melting and heat treatment,i.e.γ-TiAl single phase alloy（alloy A）,γ-TiAl ＋ α2-Ti3Al duplex phase alloy（alloy B） and γ-TiAl ＋ α2-Ti3Al ＋ Nb2Al multiple phase alloy（alloy C）.The phase stability was studied using SEM,XRD and electron probe microanalyzer.Mechanical properties were investigated through tensile tests at room temperature and 1173 K.Results show that their tensile properties are closely related to their microstructures.The deformability of alloy B is better than that of alloy A and C at room temperature due to small grain size caused by α2 phase appearance,lamellar microstructure of（γ＋α2） and tremendous γ/α2 interface.The deformability of alloy B increases significantly with increasing temperature and its elongation achieves 40.4% at 1173 K.The fracture mode of alloy B changes from brittle transgranular failure at room temperature to ductile failure at 1173 K.While,both of alloys A and C have no increased deformability at 1173 K and show brittle transgranular failure at the two temperatures.Alloy C is a kind of very brittle material at room and elevated temperature,due to Nb2Al phase appearance reducing the continues degree of（γ＋α2） lamellar structure.
出处
《稀有金属材料与工程》
SCIE
EI
CAS
CSCD
北大核心
2012年第1期38-41,共4页
Rare Metal Materials and Engineering
