简介概要

挤压次数对Mg-Zn-Zr-Re合金组织和性能的影响

来源期刊:中南大学学报(自然科学版)2008年第2期

论文作者:张振栋 刘楚明 常亚喆 李慧中 王荣 周海涛

文章页码:228 - 228

关键词:镁合金;挤压;二次挤压;第二相

Key words:magnesium alloy; extrusion; double extrusion; the second phase

摘    要:研究一次与二次挤压变形对添加稀土元素Nd和Y的ZK60镁合金显微组织及力学性能的影响。对加稀土元素Nd和Y的ZK60镁合金在5 MN立式挤压机上进行一次与二次挤压,并在国产CSS-44100电子万能拉伸机上进行拉伸试验,采用光学显微镜观察其铸态与变形态显微组织,并在KYKY-2800扫描电镜上观察断口形貌。研究结果表明:经一次挤压后,加入稀土Nd和Y后ZK60镁合金发生动态再结晶晶粒细化,力学性能显著提 高,但伸长率较低(在10%以下);经二次挤压后,在不显著降低合金强度的条件下,其塑性得到明显提高(均在10%以上)。

Abstract: The effects of single and double extrusion processes on microstructure and properties of ZK60 alloys added with Nd and Y were investigated. The single and double extrusions of ZK60 alloys added with Nd and Y were extruded on 5 MN vertical extruding machine and the specimens were tested on CSS universal electronic material testing machine. The microstructures of as-cast and as extruded specimens were analyzed by an optic microscopy and the fractographs of specimens were analyzed with the KYKY-2800 scanning electron microscope. The results show that after hot extrusion the alloy added with Nd and Y is greatly refined through dynamic recrystallization, and its tensile strength is improved, but its elongation is low and below 10%. The double extrusion can improve the alloys’ plasticity, the elongation is beyond 10%, and the strength is not obviously descended.

基金信息:国防科工委资助项目



详情信息展示

挤压次数对Mg-Zn-Zr-Re合金组织和性能的影响

张振栋1,刘楚明1,常亚喆1, 2,李慧中1,王  荣3,周海涛1

(1. 中南大学 材料科学与工程学院,湖南 长沙,410083;

2. 中国空空导弹研究院,河南 洛阳,471009;

3. 中国兵器科学研究院 宁波分院,浙江 宁波,315103 )

摘  要:研究一次与二次挤压变形对添加稀土元素Nd和Y的ZK60镁合金显微组织及力学性能的影响。对加稀土元素Nd和Y的ZK60镁合金在5 MN立式挤压机上进行一次与二次挤压,并在国产CSS-44100电子万能拉伸机上进行拉伸试验,采用光学显微镜观察其铸态与变形态显微组织,并在KYKY-2800扫描电镜上观察断口形貌。研究结果表明:经一次挤压后,加入稀土Nd和Y后ZK60镁合金发生动态再结晶晶粒细化,力学性能显著提    高,但伸长率较低(在10%以下);经二次挤压后,在不显著降低合金强度的条件下,其塑性得到明显提高(均在10%以上)。

关键词:镁合金;挤压;二次挤压;第二相

中图分类号:TG146.2         文献标识码:A         文章编号:1672-7207(2008)02-0228-06

Effect of number of extrusion times on microstructure and properties of Mg-Zn-Zr-Re alloys

ZHANG Zhen-dong1, LIU Chu-ming1, CHANG Ya-zhe1, 2, LI Hui-zhong1, WANG Rong3, ZHOU Hai-tao1

(1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;

2. China Airborne Missile Academy, Luoyang 471009, China;

3. Ningbo Branch of Ordnance Science Institute of China, Ningbo 315103, China)

 

Abstract: The effects of single and double extrusion processes on microstructure and properties of ZK60 alloys added with Nd and Y were investigated. The single and double extrusions of ZK60 alloys added with Nd and Y were extruded on 5 MN vertical extruding machine and the specimens were tested on CSS universal electronic material testing machine. The microstructures of as-cast and as extruded specimens were analyzed by an optic microscopy and the fractographs of specimens were analyzed with the KYKY-2800 scanning electron microscope. The results show that after hot extrusion the alloy added with Nd and Y is greatly refined through dynamic recrystallization, and its tensile strength is improved, but its elongation is low and below 10%. The double extrusion can improve the alloys’ plasticity, the elongation is beyond 10%, and the strength is not obviously descended.

Key words:magnesium alloy; extrusion; double extrusion; the second phase

                    


镁合金具有密度低,比强度和比刚度高,阻尼性能好,电磁屏蔽效果优异及易回收利用等优点,在电子、电器、交通、航空、航天等领域具有重要的应用价值和广阔的应用前景,被誉为21世纪最具发展前途的金属结构材料[1-3]。但是,由于镁具有密排六方(hcp)

的晶体结构,可开动的滑移系比面心立方(fcc)和体心立方(bcc)的少,因而镁合金的室温塑性较低,限制了镁合金的推广应用[4-5]。ZK60镁合金作为Mg-Zn-Zr系变形镁合金的典型代表,具有较高强度,良好的塑性和耐蚀性能,应用范围较广,但与其他合金相比也存在室温力学性能较低等缺点[6]。因此,为了提高ZK60镁合金的强度,许多研究者在ZK60镁合金中添加稀土合金元素Nd和Y[7-8]。如A. Singh等[9-10]研究稀土Y对ZK60镁合金组织和力学性能的影响,指出稀土元素Y可在ZK60镁合金中形成Mg3Zn2Y(W相)和Mg3Zn6Y相(I相),这些相具有较高硬度,良好的耐热性、耐腐蚀性能,较低的界面能,从而大大提高镁合金的室温和高温强度,但合金的伸长率较低[9-13]

然而,目前镁合金力学性能仍不高,为了提高镁合金的力学性能,本文作者主要研究挤压次数对添加稀土元素Nd和Y的ZK60镁合金显微组织及力学性能的影响。

1  实  验

 

1.1  合金的制备

采用纯Mg、纯Zn和Mg-Zr,Mg-Nd,Mg-Y中间合金制备的实验合金,合金在电阻炉中进行熔   炼,采用SF6和CO2气体进行保护。合金的化学成分如表1 所示。

表1  合金化学成分

Table 1  Chemical composition of alloy     w/%

1.2  挤压工艺

挤压前铸锭用感应炉加热,在5 MN立式挤压机上挤压,用石墨油润滑剂润滑。一次挤压的温度为  613 K,挤压比为20,挤压速度为0.5~2.0 m/min,挤压后空冷至室温。在CSS电子万能拉伸试验机上进行拉伸实验。

对合金B和合金C进行二次挤压,先将合金的直径从90 mm挤至32 mm,二次挤压前要对合金进行充分加热保温,保温时间为4 h,挤压比为10。

1.3  材料表征方法

合金显微组织采用Polyva-MET金相显微镜观察,用60 mL乙二醇+20 mL醋酸+19 mL蒸馏水+1 mL浓硝酸作浸蚀剂。在D/MAS-ⅢA X射线衍射仪上进行相分析。拉伸试验在国产CSS-44100电子万能拉伸机上进行,拉伸试样断口在KYKY-2800扫描电镜下观察断口形貌。

2  结果及分析

 

2.1  铸态显微组织分析

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