反应合成Ni-Al金属间化合物的组织及形成机理(英文)

以Ni粉和Al粉为原料,通过热爆反应合成制备Ni-Al系金属间化合物,研究了反应物摩尔比对生成物物相、组织结构和显微硬度的影响。结果表明:当Ni、Al摩尔比为1:1时,反应生成物为单一的NiAl相;当Ni、Al摩尔比为2:1时,生成物相组成为NiAl+Ni3Al相,因为非平衡冷却,NiAl含量多,呈不规则块状形态分布,Ni3Al相析出量少,主要沿初生NiAl晶界分布,当进一步提高Ni含量,且Ni、Al摩尔比为3:1时,生成物组织形态复杂,除枝晶状的β-NiAl、粗大块状和网状的γ-Ni3Al外,还有板条状和针片状的M-NiAl和不规则的块状或者尖条状的γ′-Ni3Al,这主要是由非平衡冷却和β-NiAl内的成分差异而引起的。

Microstructure and formation mechanism of Ni-Al intermetallic compounds fabricated by reaction synthesis

Ni-Al intermetallic compounds from Ni and Al powder were obtained by thermal explosion. Effects of molar ratio of Ni to Al in raw materials on the phases, microstructures and microhardness of the final products were studied. The results show that a single phase of NiAl is obtained with the composition corresponding to n(Ni):n(Al)=1:1. However, when the molar ratio of Ni to Al increases to 2:1, the product is composed of Ni₃Al and NiAl, in which NiAl phase is in the majority with an irregular morphology and Ni₃Al is in the minority mainly along the grain boundary of the NiAl. As the molar ratio of Ni to Al continues to increase to 3:1, the microstructures of the product are diversified. Lots of M-NiAl with needle-like or long lathing shape and many γ′-Ni₃Al with irregular and pointed strip-like morphology even appear besides β-NiAl with dendritic structure, γ-Ni₃Al with irregular or net-like morphology because of the non-equilibrium cooling and large difference in composition of β-NiAl.