A study of precipitates in Mg-Sn alloys

Lyu, Yang (2022). A study of precipitates in Mg-Sn alloys. University of Birmingham. Ph.D.

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Abstract

The precipitates in Mg-6Sn, Mg-6Sn-3Al and Mg-6Sn-3Zn (wt.%) alloys has been studied to determine the effect of different precipitate species on basal slip. The precipitates in peak-aged alloys were qualitatively and quantitatively analysed using electron microscopy for their chemistry, morphology, and crystallography. Two types of Mg2Sn precipitates were identified in the Mg-6Sn binary alloy, four types of Mg2Sn precipitates in the Mg-6Sn-3Al alloy and two types of Mg2Sn and two types of MgZn2 precipitates in the Mg-6Sn-3Zn alloy.
Pillar compression on specimens orientated for basal slip has been performed on the three Mg-Sn alloys to analyse the effect of different precipitate types on the deformation behaviour. The Mg-6Sn alloy exhibits the lowest resistance towards basal slip, Mg-6Sn-3Al the next highest and Mg-6Sn-3Zn exhibits the most strengthening as well as work hardening. TEM observation of as-compressed pillars indicate that basal slip was activated and was the only activated slip system.
The exact strengthening contributions of different precipitate types have been analysed quantitatively using the Orowan strengthening model. An approach to quantifying the strengthening effects of a multiple precipitate system has been proposed and applied. The as-estimated strengthening contributions from Orowan strengthening, solid solution strengthening and precipitate shearing strengthening have been analysed. The results agree adequately with the experimentally measured strength.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

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