Mn含量对粉末冶金铁铜碳低合金钢组织与力学性能的影响

采用铜粉、石墨粉和铁粉为原料,以Fe-74.8Mn-6.9C中间合金粉的形式加入Mn元素,制备粉末冶金Fe-x Mn-(2-x)Cu-0.3C(x=0,0.2,0.4,0.6,0.8,1。质量分数,%)低合金钢,研究Mn含量对该合金组织与力学性能的影响。结果表明,合金组织由铁素体和珠光体构成。加入含Mn中间合金粉对混合原料粉末的压制性能没有明显影响。随Mn含量增加,合金中孔隙的数量增多,尺寸变大;合金密度先升高后降低,Mn含量为0.4%时合金密度最大,达到7.24 g/cm~3;合金硬度先升高后降低,Mn含量为0.6%时硬度最大;合金抗弯强度下降,冲击韧性升高,Mn含量超过0.4%时二者变化均较小。因此Fe-0.6Mn-1.4Cu-0.3C合金具有较好的综合性能,硬度(HRB)和冲击韧性分别达到57.4和8.80 J/cm~2,比Fe-2Cu-0.3C合金分别提高5.3和0.82 J/cm~2,材料呈部分韧性断裂特征。     

添加W/Cr和WC/Cr3C2对铁基金刚石锯片性能的影响

以Fe-30%Cu(质量分数)合金粉末、单质Sn粉和Cu粉的混合粉末为基体,分别用W/Cr/Ni混合粉末和WC/Cr3C2/Ni混合粉末作为添加剂,制备金刚石锯片胎体材料,并利用加压烧结方法制备金刚石锯片。分析胎体材料的致密度、组织结构和力学性能以及金刚石锯片的切割性能。结果表明:胎体中添加Ni-W/Cr或Ni-WC/Cr3C2后,硬度、冲击韧性和抗弯强度最大增幅分别达到19.2%、11.7%和6.9%,致密度由96.50%降至93.1%～94.8%;胎体材料中添加2.44%W和2.44%Cr(体积分数)的金刚石锯片具有最优的干切性能,磨耗比和切割速率分别达到105.3 m/mm和1.66 m/min;添加4.36%WC和0.67%Cr3C2(体积分数)的金刚石锯片具有最优的湿切性能,磨耗比和切割速度分别达到109.6 m/mm和2.17 m/min。     

共沉淀法制备Fe-Cu基预合金粉的低温热压烧结

采用共沉淀法制备含有Co、Ni、Sn元素的Fe-Cu基预合金粉,在此预合金粉中添加25%(质量分数)的WC作为骨架相,在700~860℃温度下真空热压烧结,获得金刚石工具用金属结合剂。利用X射线衍射(XRD)和扫描电镜(SEM)对预合金粉末及金属结合剂进行形貌观察与物相分析,并测定烧结体的硬度、抗弯强度及磨耗比等力学性能。结果表明,Fe-Cu基预合金粉已形成固溶体,实现了合金化,粉末粒度较细,约在3μm左右,表面较光滑,呈不规则状。Fe-Cu基预合金粉末的原子扩散及相变主要发生在820~846℃温度范围内,在820℃下热压烧结时效果最好,胎体孔洞缺陷少,具有最佳的物理与力学性能,硬度为113.9HRB,致密度达到98.86%,抗弯强度为1306.4 MPa,结合剂对金刚石颗粒的包镶能力最强。     

碳含量对Fe-Cu-C扩散预合金粉末烧结性能的影响

扩散预合金化铁基粉末由于具有高的压缩性和成分均匀性而在粉末冶金零件中得到广泛应用。本文以扩散预合金化Fe-2%Cu(质量分数,下同)粉末为主要原料,研究了添加不同含量(0.4%、0.6%、0.8%、1.0%)的石墨粉后烧结Fe-Cu-C合金的显微组织、力学性能和尺寸变化率,并与相同成分的混合粉烧结坯进行对比。结果表明,随着碳含量的增加,Fe-Cu-C合金的烧结密度降低、硬度增加、尺寸变化率减小。扩散预合金粉末烧结后的组织更加均匀,硬度比混合粉烧结坯高5～6HRB,尺寸膨胀率仅为0.10%～0.20%,且尺寸稳定性优于混合粉烧结坯。     

放电等离子烧结制备W-20%Cu复合材料的组织及性能研究

以水热合成-共还原工艺制备的W-20%Cu(质量分数)复合粉末为原料,用SPS技术成功制备了W-20%Cu复合材料,并对其显微组织和性能进行了分析研究。结果表明:随着烧结温度的升高和保温时间的延长,W、Cu两相微观结构组织分布更为均匀,孔隙也更少,W-20%Cu复合材料的致密度、硬度和电导率也相应提高;在烧结温度950℃、保温时间5min的工艺条件下,W-20%Cu复合材料的致密度、维氏硬度、电导率分别为98.9%、HV222.8、21.7 MS/m。     

少量Mo添加对Fe-0.5Mn-0.5C烧结钢组织和力学性能的影响

采用粉末冶金方法,经1 150℃、H2气氛烧结1 h制得Fe-0.5Mn-xMo-0.5C(x=0,0.25,0.4,0.5)合金。通过金相组织观察、扫描电镜分析及力学性能测试,研究Mo添加对Fe-0.5Mn-0.5C烧结钢显微组织和力学性能的影响规律。结果表明:添加少量的Mo(≤0.5%,质量分数)可以同时提高Fe-0.5Mn-0.5C的烧结密度、抗拉强度、硬度和伸长率。当Mo含量为0.5%时,烧结体的烧结密度、抗拉强度、硬度和伸长率分别达到最大值7.10 g/cm3、426 MPa、92.2 HRB和7.58%。Mo可促进Fe-0.5Mn-0.5C坯体的致密化过程,随Mo含量增加,烧结体的显微组织中珠光体数量增加,片层间距减小;断口形貌图中解理面面积减小,韧窝数量增加。     

硅黄铜预合金粉末在金刚石工具中的应用

采用气水耦合雾化法制备了含有质量分数0.4%稀土Ce的硅黄铜预合金粉末, 在680~720 ℃热压烧结预合金粉末, 获得了致密烧结体。通过洛氏硬度计测试烧结体硬度为HRB62~65, 使用万能力学实验机测试烧结体抗弯强度为530~550 MPa, 利用扫描电子显微镜观察烧结体基体微观组织为α相黄铜, 组织中还存在蠕虫状及花状的弥散银灰色(β'+γ)相。选择添加质量分数20%的硅黄铜预合金粉末配方(铁粉+铜粉+锌粉+预合金粉末)制备花岗岩切割用金刚石刀头, 与单质粉末混合配方(铁粉+铜粉+锌粉)制备的刀头相比, 添加硅黄铜预合金粉末的刀头硬度增加22%, 抗弯强度降低8%, 刀头锋利度和使用寿命整体提升, 胎体磨粒夹杂减少, 并出现大量排屑沟槽。     

锻造温度对含钼粉末热锻合金显微组织及力学性能的影响

采用粉末热锻工艺制备Fe-1C-2Cu-xMo (x=0.50, 0.85, 1.46, 质量分数)合金, 分析锻造温度和Mo质量分数对烧结态及锻造态合金密度、显微组织、静态力学性能和动态摩擦性能的影响。结果表明: 锻造工艺能够有效提高材料密度, 锻后合金相对密度可达到98.5%, 锻态合金组织主要由贝氏体、马氏体和残余奥氏体组成。合金硬度随Mo质量分数的增加而提高, 随锻造温度的升高先降低后提高, 1050 ℃锻造Fe-1C-2Cu-1.46Mo合金硬度可达HRB116.38。Mo质量分数和锻造温度共同影响合金横向断裂强度, 1000 ℃锻造Fe-1C-2Cu-0.50Mo合金强度最高可达2608MPa, 合金断裂方式为韧脆混合型断裂。材料动态摩擦性能随Mo质量分数的增加显著提升, 当锻造温度为950 ℃且Mo质量分数为1.46%时, 材料的摩擦系数仅为0.088, 明显低于其他材料且波动较小。     

La_2O_3添加量对Fe-3Mo-3Cr-0.6V-0.5Mn-0.8C合金组织与力学性能的影响

以羰基铁粉、钼铁粉、铬铁粉、钒铁粉、锰铁粉、石墨和稀土La_2O_3为原料,采用真空烧结法制备La_2O_3改性Fe-3Mo-3Cr-0.6V-0.5Mn-0.8C合金,研究La_2O_3添加量(0.1%~0.7%,质量分数)对合金密度、硬度、组织结构以及力学性能的影响。结果表明,随La_2O_3添加量增加,合金的晶粒度明显减小,密度、硬度与抗弯强度都出现"双峰值效应"。当合金中加入0.1%La_2O_3时,合金具有最高的密度6.79 g/cm3和较高的硬度(HB)240,抗弯强度达到最大值2 300 MPa,比不含La_2O_3的合金抗弯强度提高近12%,弯曲断裂形式由脆性断裂转变为穿晶-沿晶断裂的复合断裂形式。     

CeO_2对铁基金刚石工具胎体性能的影响

在铁基预合金粉中加入不同含量的CeO_2粉末,采用热压烧结法制备金刚石工具胎体,对烧结胎体试样的微观组织和机械性能进行表征与检测。结果表明:相同工艺条件下,胎体硬度、抗弯强度与其致密度相关性很高,当CeO_2的质量分数为0.5%时,烧结胎体出现了CuNi_2Sn相,此时综合力学性能最好,致密度达到最高0.958 4,硬度达到最高值320.75HV0.3,比未添加CeO_2的增加了16.83%,抗弯强度此时也达到最高值1 515 MPa,胎体断口韧窝变深,晶界明显,断裂方式以沿晶断裂为主,晶内和晶界处分布着CeO_2颗粒,胎体内部的空隙球化、圆化明显,对胎体合金起到弥散强化作用。     

Chinalco Signed Framework Agreement for Strategic Cooperation with Harbin Municipal Government

正Last month,Chinalco signed framework agreement for strategic cooperation with Harbin Municipal Government in Harbin Xiong Weiping,Chairman of Chinalco,said that based on the strategic deployment to build world top-class mining company with the highest growth potential,Chinalco was now concentrating all efforts on making strategic transition and structural adjustment,strategic cooperation with the local governments where     

Jiangxi Promotes Jiangxi Copper Corporation To Become The World's Most Competitive Mining Company

<正>According to the latest info from Jiangxi Province State-owned Assets Supervision and Administration Commission,Jiangxi Copper Corporation was approved to become the first pilot enterprise for deepening reform.Contents of the pilot work is"Three Self"(self expansion,self decision-making,self     

Journal of Rare Earths Contents List of Vol.32(2014)

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Contributions to Baosteel Technical Research wanted

正Baosteel Technical Research,a quarterly journal,which is issued domestically and abroad,is run and sponsored by Baosteel Group Corporation.Baosteel Technical Research mainly reports the achievements in technological innovation,academic research,new product development and industrial equipment improvement by Baosteel.It will continue to follow up on hot topics and serve the company’s technological development and progress.Its readers include experts in     

Ministry of Industry and Information Technology: No Short Term Solution For Our Country’s Excess Nonferrous Metal Smelting Capacity

【正】According to the Ministry of Industry and Information Technology,the Ministry has released the 2013 Operation Report on China’s Industrial Communication Indu...     

Chinalco Signed Framework Agreement for Strategic Cooperation with Gansu Province

正Recently,Chinalco and Gansu Provincial People’s Government signed"Framework Agreement for Strategic Cooperation on Reform,Restructuring and Transition Development of Chinalco’s Electrolytic Aluminum Enterprises in Gansu",signifying that the strategic cooperation between Chinalco and Gansu Province had made new substantive progress.     

Unavoidable Economic Cycle:30% Of Nonferrous Metal Companies Were Involved In Restructuring

正Owing to continual downturn in real estate and bulk commodity markets,a number of traditional industries in China suffered unfavorable impact in performance.With the progressive disclosure of third quarter report,the no-pleasant-surprise performance of     

Baotou Rare Earth Became the World's Biggest High Performance Magnetic Material Base

正The High Performance Magnetic Material Phase II Project,an industry upgrading project implemented by Inner Mongolia Baotou IronSteel Rare Earth(Group)Hi-tech Co.,Ltd,recently basically finished equipment commissioning,signifying that the enterprise had developed the production capacity of15000 t/a Nd-Fe-B strip casting alloy and 5000t/a Nd-Fe-B magnet,thus becoming the world’s     

Introducing Two Central Enterprises to Integrate Rare Earth Industry,Shandong Rare Earth Group Breaks Surface

正With the signing of"Letter of intention for Propelling Integration of Shandong Rare Earth Enterprises"between Shandong Province Commission Of Economy and Informatization,China IronSteel Research Institute Group("China Steel Institute"),and China Rare MetalsRare Earth Co.,Ltd("China Rare Earth"),the"Shandong Rare Earth Group"jointly set up by the 3 units thus broke surface.On August 9,reporters of the China Economic Herald learned from Shandong Province     

Aluminium Production by Province or City in 2014

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