Papers by Author: Hua Nie

Abstract: The addition of strontium to Mg-Al based alloys offers good creep resistance to meet the material requirements for automotive applications. The composition, microstructure and mechanical properties of Mg-Al-Sr alloys are discussed in this paper. The effects of alloy elements such as Ca, Ti and Mn in Mg-Al-Sr alloy are summarized. Technologies for preparation of Mg-Sr master alloy were developed, including mixture method and vacuum thermal reduction method which may also be used for preparation of Mg-Al-Sr alloys.

Abstract: The Air-acetylene Flame Atomic Absorption Spectrometry (FAAS) was used to measure Sr content in Mg-Sr Alloys. The experiment conditions including acetylene flow rate, measurement height, flame wavelength were studied and the disturbing factors were discussed. It was found that, as dissolution agent of alloys and LaCl3 as the deionization agent and flame wavelength being 460.7nm, the detection limits is 1.16mg/L and the relative standard deviations is less than 0.3% and the recovery rates of Sr is more than 95%. The advantages of this method were summarized as: high sensitivity and precision, low chemistry disruption, good selectivity, good recurrence characteristics of the measuring conditions. The method is suitable for the control analysis and sample-system analysis of determination Sr content in the Mg-Sr Master Alloys.

Abstract: At the present Mg-Sr alloy is usually produced by alloy mixing process or melt-leaching-reduction process which has low productivity. A new process has been developed termed “Preparation Mg-Sr alloys using vacuum thermal reduction”. The principle and procedure of the new process were discussed in this paper. The reduction thermodynamics was analyzed, including establishing the oxygen potential diagram of Sr, Mg, Si and Al, determination of main reactions, and evaluation of Gibbs free energy in vacuum. The results showed that Mg-Sr alloys can be obtained by synchronous reduction of SrO and MgO from a mixture of MgO, SrO, Si, CaO. The equipment, reduction temperature and vacuum for the new process have been also discussed.