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(Ni,Co)3Al4。是Al-Ni-Co三元系中的一种三元相,其均匀存在范围在室温为,55—58.5A/0 Al,26—35A/0 Ni和10-15.5A/0 Co。这个三元相属立方晶系,空间群为Oh10-Ia3d,每晶胞含112个原子,在室温的点阵常数为α=11.3962?。这个结构是由64个CsCI型基本结构单位堆垛而成的一种超结构。在这64个基本结构单位中,有16个体心位置是有序地空着的,在16(b)的等效位置上构成了16个八面体空位。基本结构单位的角位置16(a)和48(f)都由Al原子占据着,而心位置48(g)则由Ni原子和Co原子无规地占据着。由于空位的存在,原子位置从其原来的CsCl型结构单位位置有所偏离;测定的结果是,xf=0.010,xg=0.369。从合金相的存在范围及原子在结构内的分布情况,这个合金相的理想化合式决定为(Ni,Co)3Al4,每单胞含16个化合式量。(Ni, Co)3Al4 is a ternary phase in the Al-Ni-Co system, the homogeneous range at room temperature being 55-58.5 A/0 Al, 26-35 A/0 Ni, and 10-15.5 A/0 Co. It belongs to the cubic system with space group Oh10-Ia3d. There are 112 atoms per unit cell, the lattice spacing at room temperature being α = 11.3962?.This structure may be considered as a superlattice built up by stacking together 64 CsCl type fundamental structural units. Among these structural units, there are 16 ‘Centre' positions left vacant in order. They occupy the 16(b) equivalent positions forming 16 octahedral voids. The ‘Corner' positions 16(α) and 48(f) are all occupied by Al atoms, while the ‘Centre' positions 48(g) are occupied at random by Ni and Co. Due to the existence of the voids, the positions originally at cube corners and centres are displaced somewhat, the parameters being xf = 0.010, xg = 0.369.Prom the homogeneous range of this alloy phase and the distribution of the various atoms in the structure, the ideal stoichiometric formula of this alloy phase may be written as (Ni, Co)3Al4. There are 16 formula weights per unit cell.
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