Formation of Amorphous ＆ Nanocrystalline Ni-W Alloys Produced by Electrodeposition and Their Mechanical Properties.

采用电解法制备了高强度纳米晶Ni-W合金。电沉积用的镀液含有硫酸镍、柠檬酸三钠、钨酸钠和氯化铵，并在不同的镀液浓度和电解条件下进行。沉积过程中共沉积氢的夹杂对合金的延展性和抗拉强度有很大影响。氢除气后，高强度的纳米晶Ni-W合金约含20.7 at。得到了平均晶粒尺寸约为3nm的% W，抗拉强度达到2300mpa左右。这种合金的高延展性也被观察到：通过180度的角度弯曲是可能的，而不会断裂。然而，在不同温度下退火这些材料时，晶粒生长发生，它们失去了延展性。为了估计纳米晶合金保持良好延展性的临界晶粒尺寸，在纳米级球形硬晶粒密集排列的情况下，考虑沿纳米晶粒密集排列的平面晶界滑动。

High-strength nanocrystalline Ni-W alloys were produced by electrodeoisition. The plating bath for the electrodeposition contained nickel sulfate, trisodium citrate, sodium tungstate and ammonium chloride, and was operated at various bath concentrations and conditions of electrolysis. The ductility and tensile strength of the deposited alloys are strongly influenced by inclusion of codeposited hydrogen during deposition process. After degassing the hydrogen, the high-strength nanocrystalline Ni-W alloy containing about 20.7 at.% W with an average grain size of about 3 nm has been obtained : the tensile strength attained to about 2300 MPa. The high ductility of this alloy was also observed : bending through an angle of 180 degree was possible without breaking. On annealing these materials at various temperatures, however, grain growth occurred and they lost their ductility. In order to estimate the critical grain size for keeping the good ductility in the nanocrystalline alloys, grain boundary sliding is considered to occur along the close-packed planes of the nanocrystalline grains under the condition where the nanoscaled spherical hard grains is represented as a densely packed array.