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时间:2020-06-01
《椭圆旋扭管反复凝熔法制备半固态A356铝合金浆料.pdf》由会员上传分享,免费在线阅读,更多相关内容在应用文档-天天文库。
1、第22卷第1期中国有色金属学报2012年1月、,01.22No.1TheChineseJournalofNonferrousMetalsJan.20l2文章编号:1004.0609(2012)1—0121—07椭圆旋扭管反复凝熔法制备半固态A356铝合金浆料刘文1,2谢水生,贾志欣,李继强,吴红兵(1.浙江大学宁波理工学院,宁波315100;2.北京有色金属研究总院,北京100022)摘要:采用椭圆旋扭管反复凝熔法制备半固态A356铝合金浆料。结果表明:椭圆旋钮管反复凝熔技术具有旋扭强制对流促进初生晶核游离、自搅
2、拌加强熔体剪切、反复凝熔促进形核的作用,可使初生n晶核演变为球形或近球形晶粒。椭圆管长短轴比、旋扭强度以及凝熔频率对半固态浆料的微观组织有显著影响。随着长短轴比、旋扭强度和凝熔频率的增大,晶粒细化和圆整效果显著提高;但长短轴比过大,容易堵塞流道;当旋扭强度超过13.5(o)/cm时,晶粒细化和圆整效果没有明显提高;当凝熔频率超过40Inn1时,晶粒细化作用不再增强,圆整度反而降低。在椭圆长短轴比为1.8:1、旋扭强度为13.5(。)/cm、凝熔频率为40的条件下可制得晶粒直径细小、形状圆整的半固态浆料。关键词:A
3、356铝合金;椭圆旋钮管;反复凝熔法;半固态;微观组织中图分类号:TG146.4文献标志码:APreparationofsemi-solidA356AIalloyslurrybyrepeatedheating—cOOlingmethodwithelliptical-twistedtubesLIUWen一,XIEShui.sheng2,JIAZhi.xin,LIJi.qiang,WUHong-bing(1.NingboInstituteofTechnology,ZhejiangUniversity,Ningbo31
4、5100,China;2.BeijingGeneralResearchInstituteforNonferrousMetals,Beijing100088,China)Abstract:Thesemi·-solidslurryofA356aluminumalloywaspreparedbytherepeatedheating·-coolingmethodwiththeelliptical—twistedtubes.Theresultsindicatethatbytherepeatedheating-cooling
5、methodwithelliptical—twistedtubesthemicrostructuresofprimarygrainsaretransformedfromdendriticorrosette-shapedtofinenet-·globularundertheactionofgrainsdetachmentduetotheforcedconvection,shearcausedbyself-stirringandheterogeneousnucleationbecauseofrepeatedheati
6、ng/cooling.Theaxialratio,twistingstrengthandheating-coolingfrequencyhavesignificantinfluencesonthemicrostructureofthesemi-solidslurry.Withtheincreaseofaxialratio,twistingstrengthandheating-coolingfrequency,thegrainrefinementandsphericityofparticleshaveremarka
7、bleimprovement.However,atthetwistingstrengthover13.5o)/cmandheating—coolingfrequencyover40岫~,thegrainrefinementdoesnothaveamuchimprovementandthesphericitydecreasesonthecontrary.Attheaxialratioof1.8:1,twistingstrengthof13.5(。l,cmandheating—coolingfrequencyof40
8、Inn~,thefavorablemicrostructureofsemi-solidA356aluminumalloycanbegeneratedbytherepeatedheating-coolingmethodwiththeelliptical-twistedtubes.Keywords:A356A1alloy;elliptical-twistedtube;repe
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