Effect of Aging Treatment on Microstructural and Mechanical Characteristics of PEO Coatings on Mg-Al Alloy

Cast Mg-6 wt pct Al alloy solution-treated at 683 K for 16 h and aged at 498 K was coated by plasma electrolytic oxidation （PEO） method.The Mg-6 wt pct Al alloy aged for 16 h exhibited the highest microhardness and wear resistance.After PEO coating,however,the microhardness and wear resistance of coatings on Mg- 6 wt pct Al alloy showed a tendency to decrease with increasing aging time,which was in aggrement with the change of thickness with aging time.In addition,the coatings on solution-treated Mg-6 wt pct Al alloy had better microhardness and wear resistance than those on aged Mg-6 wt pct Al alloys.Consequently,it can be understood that the aging treatment has a deleterious influence on the mechanical properties of coatings on Mg-6 wt pct Al alloy.

镍作为活化剂其粒度对钨粉压坯活化烧结的影响

早在一九二九年,瓦西克(Vacek)已经阐明加入少量的Ni能降低W粉坯块的烧结温度。现在已提出了解释这一作用的一些机构。然而,由于对引入的假设有争议,因此还没有一种解释能被普遍接受为正确的模型。他们都未能对压坯在烧结初始阶段产生显著致密化时,Ni可能起的作用做出具体的解释。人们一直认为,烧结性能可能取决于加Ni的方式,即意味着Ni在初始阶段的作用在烧结机构中是重要的。而Ni的初始状态,即Ni的初始分布和粒度也是重要的,因为添加物的物理状态明显的与将其加入W粉所采用的方法有关。例如。