Journal
MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
Volume 562, Issue -, Pages 152-160Publisher
ELSEVIER SCIENCE SA
DOI: 10.1016/j.msea.2012.11.016
Keywords
Cooling rate; Mg-10Gd-3Y-0.5Zr; Magnesium alloy; Sand casting; Mechanical properties
Categories
Funding
- National Natural Science Foundation of China [51275295]
- SAST-SJTU Aerospace Advanced Technology Joint Research Centre [USCAST2012-15]
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The present study investigated the effect of cooling rate on the microstructure and mechanical properties of sand casting Mg-10Gd-3Y-0.5Zr alloy with a cooling rate range of 0.7-3.6 degrees C/s. When the cooling rate was increased, the average grain size of alpha-Mg decreased from 59 pm to 39 pm, the volume fraction of the second phase increased from 17.6% to 24.5%, and the eutectic compound exhibited continuous network instead of coarsening discontinuous network of plate-shaped microstructure. Energy-dispersive X-ray test results suggested that solute content of RE elements (Gd and Y) was low within the area near the grain boundary of a-Mg with high cooling rate, and solid-solution reaction occurred in the sand casting process. In addition, Vickers hardness (HV) testing indicated that HV increased with the increasing cooling rate, and the volume fraction of second phase (V) played a main role in hardness of the alloys. There was a linear relationship between them, the fitting function was HV=1.25 V+63.05, R-2=0.9989. Tensile strength test showed that both of ultimate tensile strength (UTS) and tensile yield strength (TYS) first increased and then decreased with the increasing cooling rate. Based on fracture observations, the types of fracture surface characteristics are correspondingly classified into three modes, transgranular, dimple-like fracture and intergranular fracture with the increasing cooling rate. (C) 2012 Elsevier B.V. All rights reserved.
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