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

采用电沉积法制备了高强度纳米晶Ni-W合金。用于电沉积的镀浴含有硫酸镍、柠檬酸三钠、钨酸钠和氯化铵，并且在各种浴浓度和电解条件下操作。在沉积过程中，共沉积氢的夹杂物对沉积合金的塑性和抗拉强度有很大的影响。经除氢处理后，可获得含20.7at.%左右的高强度纳米晶Ni-W合金获得了平均晶粒尺寸约为3 nm的W，抗拉强度达到约2300 MPa。还观察到该合金的高延展性：可以弯曲180度而不断裂。然而，在不同温度下退火这些材料时，发生晶粒生长，并且它们失去了延展性。为了估计在纳米晶合金中保持良好延展性的临界晶粒尺寸，晶界滑动被认为是在纳米尺度球形硬晶粒被表示为密集排列的条件下沿纳米晶晶粒的密集排列平面沿着发生。

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.