Preparation of corrosion-resistant amorphous Ni–Cr–P–B bulk alloys containing molybdenum and tantalum
Preparation of corrosion-resistant amorphous Ni–Cr–P–B bulk alloys containing molybdenum and tantalum
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DOI：
10.1016/s0921-5093(00)01571-9
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发表时间：
2001-05
期刊：
影响因子：
6.4
通讯作者：
H. Habazaki;Takeaki Sato;A. Kawashima;K. Asami;K. Hashimoto
中科院分区：
文献类型：
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作者：
H. Habazaki;Takeaki Sato;A. Kawashima;K. Asami;K. Hashimoto
用铜模铸造法获得了直径为1和2 mm的圆柱形非晶Ni-15 Cr-10 Mo-16 P-4 B和Ni-（10和15）Cr-5 Ta-16 P-4 B合金。这些非晶合金在303 K的6 M HCl中自发钝化，直径为1 mm的块体合金在303 K的6 M HCl中的耐蚀性与相同成分的快淬合金薄带相当。动电位极化曲线表明，直径为2 mm的Ni-10 Cr-5 Ta-16 P-4 B合金的腐蚀速率约为直径为1 mm的Ni-10 Cr-5 Ta-16 P-4 B合金腐蚀速率的3倍，但X射线衍射图谱表明两种尺寸的试样均为非晶态。用高分辨透射电子显微镜进一步详细的结构分析表明，只有直径为2 mm的样品在非晶基体中存在2- 3 nm尺寸的fcc镍沉淀。直径为2 mm的Ni-15 Cr-10 Mo-16 P-4 B合金含有较大的fcc镍沉淀物，尺寸约为20 nm，显示出比直径为1 mm的非晶单相合金高约两个数量级的阳极电流密度。因此，主动溶解在6 M HCl中的纳米晶镍相的沉淀对非晶Ni-Cr-（Mo或Ta）-P-B合金的耐腐蚀性有害，尽管较小尺寸的沉淀物的危害较小。
Cylindrical amorphous Ni–15Cr–10Mo–16P–4B and Ni–(10 and 15)Cr–5Ta–16P–4B alloys of 1 and 2mm in diameter have been obtained by a copper mould casting method. These amorphous alloys are spontaneously passive in 6M HCl at 303K, and the corrosion resistance of the bulk alloys of 1mm diameter in 6M HCl at 303K is as high as that of the rapidly quenched alloy ribbons with the same composition. However, potentiodynamic polarization reveals that the corrosion rate of the Ni–10Cr–5Ta–16P–4B alloy of 2mm diameter is about three times higher than that of the alloy of 1mm diameter, though both sizes of the specimens are identified to be amorphous from X-ray diffraction patterns. The further detailed structural analysis using high resolution transmission electron microscopy indicates the presence of fcc nickel precipitates, 2–3nm size, in the amorphous matrix only for the specimen of 2mm diameter. The Ni–15Cr–10Mo–16P–4B alloy of 2mm diameter contains larger precipitates, about 20nm size, of fcc nickel, showing about two orders of magnitude higher anodic current density than the amorphous single phase alloy of 1mm diameter. Thus, the precipitation of a nanocrystalline nickel phase, which actively dissolves in 6M HCl, is detrimental to the corrosion resistance of the amorphous Ni–Cr–(Mo or Ta)–P–B alloys, although the smaller size of the precipitates is less detrimental.