(1. 重慶大學(xué) 材料科學(xué)與工程學(xué)院，重慶 400043；2. 南陽理工學(xué)院 機(jī)電系，南陽 473004；
3. 重慶大學(xué) 國家鎂合金研究中心，重慶 400044)
摘 要: 利用金相顯微鏡(OM)、掃描電鏡(SEM)和萬能材料試驗(yàn)機(jī)，對ZK20和ZK20+0.5Nd鎂合金不同溫度均勻化退火后的組織以及擠壓態(tài)合金的力學(xué)性能進(jìn)行研究。退火溫度分別為603、633、663、693 K，保溫時間均為10 h。結(jié)果表明：均勻化退火使鑄錠中的Mg-Zn和Mg-Nd-Zn合金相不斷固溶到基體中，同時枝晶偏析大幅度降低；與未均勻化相比，ZK20+0.5Nd合金均勻化退火后擠壓，擠壓態(tài)塑性有較大幅度提高，而強(qiáng)度并沒有降低；稀土Nd細(xì)化ZK20合金晶粒，使均勻化退火提高擠壓態(tài)合金塑性的作用更加明顯，增強(qiáng)均勻化退火效果。對于ZK20合金，663 K，10 h是最優(yōu)的均勻化退火工藝；對于ZK20+0.5Nd合金，693 K，10 h是較合適的退火工藝。
關(guān)鍵字: 鎂合金；ZK20鎂合金；均勻化退火；釹；擠壓；組織；力學(xué)性能
microstructure and properties of ZK20 Mg alloy
（1. College of Materials Science and Engineering, Chongqing University, Chongqing 400043, China;
2. Department of Mechanic and Electronic Engineering, Nanyang Institute of Technology, Nanyang 473004, China;
3. National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044, China）
Abstract:The effects of homogenizing annealing of ingot on as-annealed microstructure and as-extruded mechanical properties of ZK20 and ZK20+0.5Nd magnesium alloy were investigated by room tensile test, optical microscopy and scanning electron microscopy. The annealing temperatures were 603, 633, 663, 693 K, separately, and the holding time was 10 h. The results show Mg-Zn and Mg-Nd-Zn compounds observed in the cast ingot disappear gradually with increasing annealing temperature, and the dendritic segeration decreases dramatically. The elongation of as-extruded ZK20+0.5Nd alloy after homogenizing annealing is higher than that of the alloy without annealing while its strengh remains unchanged. The Nd addition can refine the grain and improve the ductility of as-extruded alloy, and the effect of homogenizing annealing on the elongation of ZK20 alloy is enhanced as a result. It can be concluded that the better homogenizing annealing process are 663, 10 h for ZK20 and 693, 10 h for ZK20+0.5Nd.
Key words: Mg alloy; ZK20 Mg alloy; homogenization annealing; Nd; extrusion; microstructure; mechanical properties
