(甘肅工業(yè)大學(xué) 材料科學(xué)與工程學(xué)院，蘭州 730050)
摘 要: 研究了未變質(zhì)處理和變質(zhì)處理的AZ91D鎂合金在半固態(tài)等溫?zé)崽幚磉^(guò)程中的組織演變，并對(duì)其組織演變機(jī)理進(jìn)行了探討。結(jié)果表明 AZ91D鎂合金在液-固相區(qū)570℃等溫處理時(shí)，未變質(zhì)處理的δ相由粗大的樹(shù)枝晶演變?yōu)榇髩K狀，隨后δ相發(fā)生熔化分離，并在半固態(tài)等溫過(guò)程中演變?yōu)榍驙睿跎嘧钚〕叽缈蛇_(dá)50～80μm； 變質(zhì)處理的初生δ相由等軸晶演變?yōu)樾K狀，隨后進(jìn)一步熔化分離為更細(xì)小的塊狀，接著逐漸演變?yōu)榍驙罱M織，初生相最小尺寸可達(dá)20～60μm。等溫處理時(shí)間過(guò)長(zhǎng)時(shí)，兩種組織都會(huì)發(fā)生合并長(zhǎng)大。
關(guān)鍵字: 鎂合金； 半固態(tài)成形； 半固態(tài)等溫?zé)崽幚恚磺驙罱M織
during semi-solid isothermal heat treatment
（College of Materials Science and Engineering，
Gansu University of Technology， Lanzhou 730050， P.R.China）
Abstract:The structure evolution of AZ91D magnesium alloy and the modified AZ91D magnesium alloy during semi-solid isothermal heat treatment was studied， and its transformation mechanism was also discussed. It was found that， when AZ91D magnesium alloy is treated at semi-solid temperature 570 ℃， the primary δphase changes from the large dendritic structure to the large nubbly， and then to be melt and separated into the small nubbly. With isothermal times increasing， the small nubbly changes to spheroidal grains and the primary δ phase is formed about 50～80μm. Therefore， the primary δ phase which is modified changes from equiaxed grains to small nubbly， then it is separated into smaller nubbly. With increasing isothermal times， it changs to the smaller spheroidal grains than its non-modification does and is formed about 20～60 μm.
Key words: magnesium alloy; semi-solid forming； semi solid isothermal heat-treatment； spheroidal structure
