通过金相显微镜、SEM及XRD等观察手段研究了触变成型AZ91D镁合金铸件固溶、时效处理时显微组织的演变.结果表明:触变成型AZ91D镁合金在415℃时固溶处理时β相溶解入α-Mg固溶体的速度比高压压铸的快.在固溶处理初期,铝元素从β相扩散至块状初生α-Mg相,导致块状初生α-Mg晶粒周围形成富铝晕圈.时效处理时,触变成型铸件在5 h左右硬度达到峰值,高压压铸铸件在12 h左右达到峰值.触变成型铸件时效析出方式存在片层状不连续析出和针状连续析出两种.
Microstructure and mechanical properties of a thixoformed AZ91D magnesium alloy in as-cast and heat treatment conditions were characterised by means of optical microscope(OM),scanning electron microscopy(SEM),XRD and hardness tests.The results show that the thixoformed AZ91D magnesium alloy exhibits a faster β phase dissolution rate than that in the high pressure die-cast alloy under solution treatment at 415 ℃.Al-rich halos are observed at the early stage of solution treatment because Al diffuses from the β phase to the primary α-Mg phase.During aging at 216 ℃,the thixoformed AZ91D magnesium alloy reaches its peak hardness at about 5 h while the high pressure die-cast alloy at 12 h.Both discontinuous and continuous precipitates of the β phase in the thixoformed alloy are observed.
参考文献
| [1] | Kang C G;Junk H K .Semisolid forming process numerical simulation and experimental study[J].Metallurgical and Materials Transactions,1972,32(02):363-371. |
| [2] | Cerri E;Evangelists E;Spigarelli S et al.Effects of thermal treatment on microstructure and mechanical properties in thixocast 319 aluminum alloy[J].Materials Science and Engineering A,2000,284(01):254-260. |
| [3] | C. G. Kang;Y. J. Jung;S. W. Youn .Horizontal reheating of aluminum alloys and semi-solid casting for a near net shape compressor component[J].Journal of Materials Processing Technology,2003(2/3):158-171. |
| [4] | Koren Z;Rosenson H;Gutman E M.Development of semisolid casting for AZ91 and AM50 magnesium alloys[J].Journal of Light Metals,2002(02):81-87. |
| [5] | 王开,刘昌明,翟彦博.AZ91D镁合金触变铸造件热处理前后的组织与性能[J].特种铸造及有色合金,2008(01):28-30. |
| [6] | 唐钟雪,李元东,郝远.时效处理对触变成形AZ91D镁合金组织和力学性能的影响[J].热加工工艺,2005(03):4-7. |
| [7] | Y. Wang;G. Liu;Z. Fan .Microstructural evolution of rheo-diecast AZ91D magnesium alloy during heat treatment[J].Acta materialia,2006(3):689-699. |
| [8] | 陈振华.镁合金[M].北京:机械工业出版社,2000 |
| [9] | 于海朋,王峰,于宝义,马永涛.工艺参数和热处理对压铸AZ91D力学性能的影响[J].特种铸造及有色合金,2002(02):27-28. |
| [10] | Clark J B .Age hardening in a Mg-9wt% Al ahoy[J].Acta Metallurgica,1968,16(02):141-152. |
| [11] | 王越,吴伟,刘正,宋德仁,李锋,刘重阳.AZ91HP非连续析出的组织转变特点[J].沈阳工业大学学报,2000(06):467-470. |
- 下载量()
- 访问量()
- 您的评分：
-
10%
-
20%
-
30%
-
40%
-
50%