晶面指数对高纯铝表面腐蚀发孔的影响

Influence of surface indices of high purity aluminum crystals on initiation process of pit etching

采用含有盐酸、硝酸、氢氟酸的混合溶液腐蚀了从高纯铝锭上切割出的单晶{100}和{124}表面。定量统计两表面腐蚀孔密度随腐蚀时间的变化,并对变化规律进行了非线性拟合。研究表明,试样表面发生点蚀的位置为表面位错露头,其腐蚀发孔的难易程度与相应的位错应变能有关。研究表明,{100}面潜在发孔位置密度高于{124}面,而初始发孔率低于{124}面。{124}面较高的表面能使腐蚀孔生长较快,造成腐蚀后期其孔密度明显低于{100}面。

The solution containing hydrochloric acid, nitric acid and hydrofluoric acid was used to etch the { 100} and { 124} surfaces of single crystal which were cut from ingot of high purity aluminum. The densities evolvement of pitting holes on the surfaces of the samples was quantitatively and statistically analyzed during the etching process, of which the regularity was obtained by the nonlinear fitting regression. It was observed that the pit etching initiates at the locations of dislocation ends on the samples surface. The difficulty of the pit etching was related to the strain energy of corresponding dislocations. The results show that density of potential pit nucleation on {100} surface is higher than that on {124} surface, and the primary nucleation rate of pit etching on { 100 } surface is lower than that on { 124} surface. Pitting holes on { 124 } surface grow faster than those on { 100} surface because the surface energy on { 124} surface is higher than that on { 100}, which leads to obviously lower pitting hole density on { 124} after long etching treatment.