摘要：鎂及其合金是迄今工程應用中最輕的結構材料之一，純鎂的密度為1.74g/cm3，具有高的比強度（強度/密度），可鑄性好，導熱導電能力強等，但是純鎂的強度不高，耐腐蝕性較低。本文以純鎂為研究對象，通過對鑄態(tài)純鎂、退火態(tài)純鎂及其相應的等通道變形（ECAP），研究ECAP變形對純鎂的顯微組織和顯微硬度的影響。本文采用12mm/min和6mm/min速度的ECAP變形對純鎂進行1道次處理，實驗結果表明，與鑄態(tài)純鎂相比，變形后的純鎂得到了顯著的細化，顯微硬度也得到了提高。

　　　對鑄態(tài)純鎂試樣在保護氣氛下（氬氣）進行退火處理，退火后純鎂經過ECAP后的細化效果更加明顯，退火態(tài)純鎂的粗大晶粒被破碎成細小的晶粒，晶粒尺寸從~400μm減小到~100μm。經過對變形前后顯微硬度的測量，ECAP變形純鎂的顯微硬度也要高于鑄態(tài)純鎂的硬度。

　　　在無保護氣氛條件下，對鑄態(tài)純鎂進行不同溫度下的退火處理，鑄態(tài)晶粒尺寸~4mm，500℃退火后的晶粒尺寸~1.5mm，550℃退火后晶粒尺寸~0.2mm，不難看出，退火溫度越高，退火后晶粒細化越明顯。與無保護氣氛下退火純鎂相比，在500℃保護氣氛下退火時，晶粒尺寸就已經細化到~0.4mm，保護氣氛退火細化效果更明顯。

關鍵詞：純鎂；等通道變形；退火；組織；性能

Abstract:Magnesium and its alloy is one of the lightest structural materials in the engineering applications so far. The density of pure magnesium is 1.74g/cm3, it has excellent performances, such as the high strength/weight ratio, castability and electrical conductivity. In this paper, the pure magnesium as the research object was used, the microhardness and microstructure of the as-cast pure magnesium, heat treatment of as-cast pure magnesium and the corresponding pure magnesium processed by ECAP were investigated. The experiment processed the pure magnesium by 1 pass in the speed of 12mm/min and 6mm/min, the results of the experiment show that, coarse grains in cast pure magnesium was broken into smaller grains, and its microhardness was improved.

　　　Annealing the as-cast pure magnesium in protective atmosphere, the annealed pure magnesium processed by ECAP shows better refined ability. After annealing, the coarse grains were broken into smaller grains, the grain size was reduced from the initial ~400 μ m to ~100 μ m after one ECAP pass. By measuring the microhardness of the samples before and after deformation, the pure magnesium after ECAP shows the higher microhardness.

　　　In unprotective atmosphere condition , the pure magnesium was annealed in different temperatures, the grain size of the pure magnesium was ~4mm, the grain size affter annealing at 500℃ was ~1.5mm, the grain size after annealing at 550℃ was ~0.2mm.It is obvious to see that the higher temperature, the smaller the grain. Compared with the condition in unprotective atmosphere, annealing at 500℃ in protective atmosphere ,the grain size was ~0.4mm. Annealing in protective atmosphere shows better grain refinement.

Key words: pure magnesium; ECAP; anneal; structure; property.