Solidification behaviour of Al–7% Si–0.3% Mg during rotary spray forming
A. E. W. JARFORS
JOURNAL OF MATERIALS SCIENCE
abstract:The solidication behaviour of an Al 7% Si 0.3% Mg alloy during rotary spray forming was studied. The ability to form a coating was insensitive to the thermal processing parameters, yielding material exchangess greater than 90%. The level of porosity varied typically between 1.5 and 4.75%. The dendrite arm spacing was evaluated and used to estimate the cooling rates. Typical dendrite secondary arm spacings were of the order of 3 m, 12 m and 25 m, corresponding to cooling rates of 4630 K s1, 72 K s1 and 8 K s1, respectively. The fraction primary precipitation was experimentally determined and the partition coefcient calculated indirectly using the Scheil equation. The partition coefcient is increased during rotary spray forming. This is explained by the presence of trapped vacancies at the solidication front. The vacancies change the solid s free energy and thus change the phase diagram and the partition coefcient. A simplistic analysis of entrapment and condensation of vacancies and their inuence on the partition coefcient is made.
keywords:Plasma spraying; rotary spray forming
本站文章未经允许不得转载；如欲转载请注明出处，北京桑尧科技开发有限公司网址：http://www.sunspraying.com/
|
