Volume 0,Issue 7,2003 Table of Contents
2003(7):481-485.
Abstract:
The mechanisms of superplastic deformation and their accommodation for TiAl based alloys are reviewed in different experimental conditions such as composition, microstructure, grain size, process parameters etc.in the present paper. The true stress-true strain relationships during superplastically deforming are also introduced and analyzed in relative detail.
The mechanisms of superplastic deformation and their accommodation for TiAl based alloys are reviewed in different experimental conditions such as composition, microstructure, grain size, process parameters etc.in the present paper. The true stress-true strain relationships during superplastically deforming are also introduced and analyzed in relative detail.
2003(7):486-489.
Abstract:
研究了低钙磷比溶液电沉积缺钙羟基磷灰石生物陶瓷涂层在水热合成和700℃,800℃,900℃焙烧后的相组成和显微组织结构;用扫描电镜(SEM)、X射线衍射(XRD)和透射电镜(TEM)对涂层进行分析。结果表明:在电沉积液Ca/P比1.30,沉积液温度25℃,电压4V条件下,Ti基体表面沉积了片状和条状HAP和CaHPO4·2H2O混合相涂层;在pH值为12的碱液中,150℃和200℃水热合成4h后涂层由针状纯HAP组成,Ca/P比约为1.61,且随着水热合成温度的升高,晶体结晶度提高,但晶体无明显长大趋势;700℃焙烧后,涂层仍由纯HAP组成,只是晶体因失水而发生团聚;800℃焙烧后,部分HAP发生分解,生成β-Ca3(PO4)2,且HAP与β-Ca3(PO4)2的体积比为90∶10,形貌为块状和板条状,其表面附着许多细小的针状颗粒;900℃焙烧后,β-Ca3(PO4)2的含量增加,HAP与β-Ca3(PO4)2的体积比为74∶26,小颗粒团聚成较大的块状和板条状颗粒。由此制备了对骨组织生长更有利的HAP+β-Ca3(PO4)2双相涂层结构。
研究了低钙磷比溶液电沉积缺钙羟基磷灰石生物陶瓷涂层在水热合成和700℃,800℃,900℃焙烧后的相组成和显微组织结构;用扫描电镜(SEM)、X射线衍射(XRD)和透射电镜(TEM)对涂层进行分析。结果表明:在电沉积液Ca/P比1.30,沉积液温度25℃,电压4V条件下,Ti基体表面沉积了片状和条状HAP和CaHPO4·2H2O混合相涂层;在pH值为12的碱液中,150℃和200℃水热合成4h后涂层由针状纯HAP组成,Ca/P比约为1.61,且随着水热合成温度的升高,晶体结晶度提高,但晶体无明显长大趋势;700℃焙烧后,涂层仍由纯HAP组成,只是晶体因失水而发生团聚;800℃焙烧后,部分HAP发生分解,生成β-Ca3(PO4)2,且HAP与β-Ca3(PO4)2的体积比为90∶10,形貌为块状和板条状,其表面附着许多细小的针状颗粒;900℃焙烧后,β-Ca3(PO4)2的含量增加,HAP与β-Ca3(PO4)2的体积比为74∶26,小颗粒团聚成较大的块状和板条状颗粒。由此制备了对骨组织生长更有利的HAP+β-Ca3(PO4)2双相涂层结构。
2003(7):490-493.
Abstract:
The coercivity mechanism of HDDR anisotropic Nd Fe B magnet is investigated. The measurements of magnetization curve and different susceptibilities as well as the observations of microstructure are performed. It is concluded that the magnetic hardening of the magnet is due to the pinning of domain walls at grain boundaries and the Nd rich boundary phase that distributes homogeneously around some colonies composed of fine Nd2Fe14B grains. The coercive field is mainly determined by the pinning of domain walls by the Nd rich boundary phase. The conclusions mentioned above are in good agreement with the theoretical calculation of the intrinsic coercivity of the magnet. Furthermore, experimental verification is carried out and the processes for improving the coercivity of the magnets are proposed.
The coercivity mechanism of HDDR anisotropic Nd Fe B magnet is investigated. The measurements of magnetization curve and different susceptibilities as well as the observations of microstructure are performed. It is concluded that the magnetic hardening of the magnet is due to the pinning of domain walls at grain boundaries and the Nd rich boundary phase that distributes homogeneously around some colonies composed of fine Nd2Fe14B grains. The coercive field is mainly determined by the pinning of domain walls by the Nd rich boundary phase. The conclusions mentioned above are in good agreement with the theoretical calculation of the intrinsic coercivity of the magnet. Furthermore, experimental verification is carried out and the processes for improving the coercivity of the magnets are proposed.
2003(7):494-497.
Abstract:
利用高温X射线衍射研究了纯Cu，纯Al，Cu75Al25，Cu71Al25Ni4(原子分数，％)液态结构，获得了结构因子。研究结果表明：纯Cu和纯Al熔体结构因子主峰前曲线均呈光滑的抛物线状；而Cu75Al25熔体的结构因子曲线主峰前则出现预峰；加入Ni后，即Cu71Al25Ni4熔体的结构因子曲线上预峰明显增强。根据预峰的特性，提出两液态结构的原子模型，即由八面体结构共享顶点形成的原子团簇与无规密堆积原子分布区域组成。
利用高温X射线衍射研究了纯Cu，纯Al，Cu75Al25，Cu71Al25Ni4(原子分数，％)液态结构，获得了结构因子。研究结果表明：纯Cu和纯Al熔体结构因子主峰前曲线均呈光滑的抛物线状；而Cu75Al25熔体的结构因子曲线主峰前则出现预峰；加入Ni后，即Cu71Al25Ni4熔体的结构因子曲线上预峰明显增强。根据预峰的特性，提出两液态结构的原子模型，即由八面体结构共享顶点形成的原子团簇与无规密堆积原子分布区域组成。
2003(7):498-501.
Abstract:
采用化学溶液法混料，然后用氢还原氮化法制备出具有包覆结构的Si3N4／BN纳米复合粉体，复合粉热压后获得较高强度，同时又具有良好加工性能的复相陶瓷。扫描电镜(SEM)，X射线衍射(XRD)分析表明：复相陶瓷中氮化硼以六方晶(h-BN)均匀分布于以α-Si3N4为基体相的晶界与晶内，并抑制α-Si3N4的晶粒长大使基体晶粒细化。良好加工性能的获得是由于h-BN易沿其层间解理以及h-BN与α-Si3N4两相由于热膨胀失配产生的弱界面易在剪切方向剥层所致。
采用化学溶液法混料，然后用氢还原氮化法制备出具有包覆结构的Si3N4／BN纳米复合粉体，复合粉热压后获得较高强度，同时又具有良好加工性能的复相陶瓷。扫描电镜(SEM)，X射线衍射(XRD)分析表明：复相陶瓷中氮化硼以六方晶(h-BN)均匀分布于以α-Si3N4为基体相的晶界与晶内，并抑制α-Si3N4的晶粒长大使基体晶粒细化。良好加工性能的获得是由于h-BN易沿其层间解理以及h-BN与α-Si3N4两相由于热膨胀失配产生的弱界面易在剪切方向剥层所致。
6 Preparation and Crystallization Process of VO2 Nanometer Powders by Liquid Phase Hydrolysis Method
2003(7):502-505.
Abstract:
研究了以VOSO4为前驱体，应用液相沉淀法制取VO2纳米粉的制粉技术以及VO2粉末的晶化过程，采用TGA，DSC，XRD，TEM等测试手段对所得粉的物理特性进行了测试分析。试验结果表明：所制取的VO2粉末颗粒粒径介于10nm-30nm之间，该粉体经400％真空热处理10h可完全实现晶化，相变温度为65％。
研究了以VOSO4为前驱体，应用液相沉淀法制取VO2纳米粉的制粉技术以及VO2粉末的晶化过程，采用TGA，DSC，XRD，TEM等测试手段对所得粉的物理特性进行了测试分析。试验结果表明：所制取的VO2粉末颗粒粒径介于10nm-30nm之间，该粉体经400％真空热处理10h可完全实现晶化，相变温度为65％。
2003(7):506-509.
Abstract:
以N2和Ar的混合气为气源，在Ti6Al4V表面离子渗氮形成渗氮层。对渗层的相结构、表面粗糙度、显微硬度及与基体的结合强度等进行了测试分析，并用球-盘滑动磨损试验机对渗层的摩擦学性能进行了研究。结果表明：在N2／Ar=1：1，900℃的渗氮条件下，渗氮层主要由化合物Ti2N，TiN和氮在α-Ti中的固溶体α相等相组成；渗氮后试样的表面粗糙度增大；渗氮层的硬度较基材Ti6Al4V有很大提高，且与基体间有较好的结合强度；在球-盘滑动磨损试验中，渗氮层无减摩效果，但其耐磨性较基材Ti6Al4V大大增强。
以N2和Ar的混合气为气源，在Ti6Al4V表面离子渗氮形成渗氮层。对渗层的相结构、表面粗糙度、显微硬度及与基体的结合强度等进行了测试分析，并用球-盘滑动磨损试验机对渗层的摩擦学性能进行了研究。结果表明：在N2／Ar=1：1，900℃的渗氮条件下，渗氮层主要由化合物Ti2N，TiN和氮在α-Ti中的固溶体α相等相组成；渗氮后试样的表面粗糙度增大；渗氮层的硬度较基材Ti6Al4V有很大提高，且与基体间有较好的结合强度；在球-盘滑动磨损试验中，渗氮层无减摩效果，但其耐磨性较基材Ti6Al4V大大增强。
2003(7):510-513.
Abstract:
研究了TiC，TiB2两种钛化物在纯铝熔体中的行为及其对熔体粘度的影响规律。720℃时的测量数据表明，以Al-5Ti-1B和Al-3Ti-0．15C形式加入微量TiB2或TiC的铝熔体，其粘度增加30％左右；分析了熔体粘度突变的原因，并提出了钛化物／铝熔体界面过渡区的假设。上述熔体经一段时间的保温后，出现了随熔体温度降低而粘度降低的异常变化，从钛化物／铝熔体界面过渡区的形成和整体的沉淀得到了合理的解释。固态条件下钛化物粒子周围存在Ti浓度的梯度分布也间接证实了熔体条件下钛化物／铝熔体界面过渡区的存在。
研究了TiC，TiB2两种钛化物在纯铝熔体中的行为及其对熔体粘度的影响规律。720℃时的测量数据表明，以Al-5Ti-1B和Al-3Ti-0．15C形式加入微量TiB2或TiC的铝熔体，其粘度增加30％左右；分析了熔体粘度突变的原因，并提出了钛化物／铝熔体界面过渡区的假设。上述熔体经一段时间的保温后，出现了随熔体温度降低而粘度降低的异常变化，从钛化物／铝熔体界面过渡区的形成和整体的沉淀得到了合理的解释。固态条件下钛化物粒子周围存在Ti浓度的梯度分布也间接证实了熔体条件下钛化物／铝熔体界面过渡区的存在。
2003(7):514-517.
Abstract:
研究了组织形态对TC4钛合金应力松弛行为的影响。结果表明：200℃时等轴组织的抗应力松弛性能好于魏氏组织；400℃和600℃时魏氏组织的抗应力松弛性能稍高于等轴组织。不同组织的塑性应变速率-应力曲线具有相似的形状。等轴组织晶粒发生轻微的长大，魏氏组织在发生粗化的同时，条状物长径比减小，有球化的倾向。
研究了组织形态对TC4钛合金应力松弛行为的影响。结果表明：200℃时等轴组织的抗应力松弛性能好于魏氏组织；400℃和600℃时魏氏组织的抗应力松弛性能稍高于等轴组织。不同组织的塑性应变速率-应力曲线具有相似的形状。等轴组织晶粒发生轻微的长大，魏氏组织在发生粗化的同时，条状物长径比减小，有球化的倾向。
2003(7):518-521.
Abstract:
The crystallization behavior of Zr Al Ni Cu bulk amorphous alloy during continuous heating is investigated. The results show that with increasing of heating rates, all the specific temperatures (Tg, Tx, and Tp) shift to the high temperature region, and the crystallization enthalpy and the enlarged supercooled liquid region increase, while the crystallized volume fraction corresponding to the peak temperature Tp decreases. Using Kissinger and Doyle plots, the activation crystallization energy can be evaluated. During continuous heating, the activation energy increases with increasing of the crystallized volume fraction at the early stage of crystallization, then decreases slightly and finally drops sharply. The value of activation energy obtained from Kissinger plots is a bit larger than that obtained from Doyle plots due to the change of the crystallized volume fraction at the specific temperature for different heating rates.
The crystallization behavior of Zr Al Ni Cu bulk amorphous alloy during continuous heating is investigated. The results show that with increasing of heating rates, all the specific temperatures (Tg, Tx, and Tp) shift to the high temperature region, and the crystallization enthalpy and the enlarged supercooled liquid region increase, while the crystallized volume fraction corresponding to the peak temperature Tp decreases. Using Kissinger and Doyle plots, the activation crystallization energy can be evaluated. During continuous heating, the activation energy increases with increasing of the crystallized volume fraction at the early stage of crystallization, then decreases slightly and finally drops sharply. The value of activation energy obtained from Kissinger plots is a bit larger than that obtained from Doyle plots due to the change of the crystallized volume fraction at the specific temperature for different heating rates.
2003(7):522-525.
Abstract:
研究了Y2O2S：Tb纳米晶的发光性质和能量传递过程，根据浓度猝灭曲线分析了纳米Y2O2S中引起^5D3和^5D4能级浓度猝灭的相互作用类型分别为电偶极-电偶极和交换相互作用。纳米Y2O2S中Tb离子^5D3-^7F3跃迁的发光寿命与相同掺杂浓度的体材料相比明显缩短，根据引起浓度猝灭的相互作用类型对发光衰减曲线进行拟合，得到理论和试验一致的结果。
研究了Y2O2S：Tb纳米晶的发光性质和能量传递过程，根据浓度猝灭曲线分析了纳米Y2O2S中引起^5D3和^5D4能级浓度猝灭的相互作用类型分别为电偶极-电偶极和交换相互作用。纳米Y2O2S中Tb离子^5D3-^7F3跃迁的发光寿命与相同掺杂浓度的体材料相比明显缩短，根据引起浓度猝灭的相互作用类型对发光衰减曲线进行拟合，得到理论和试验一致的结果。
2003(7):526-529.
Abstract:
The influence of cementum extracts on the initial attachment of osteoblast has been measured by using the rat of cell attachment. The attachment index after 1,3, and 6 d, and the orientation index after 3 and 6 d have been obtained by the image analysis. It is observed that the extracts of cementum enhance the attachment and migration of osteoblast on the polished titanium surface. It is proposed that the cementum extracts can be used as the implantal coating materials in order to achieve an ideal osteointegration.
The influence of cementum extracts on the initial attachment of osteoblast has been measured by using the rat of cell attachment. The attachment index after 1,3, and 6 d, and the orientation index after 3 and 6 d have been obtained by the image analysis. It is observed that the extracts of cementum enhance the attachment and migration of osteoblast on the polished titanium surface. It is proposed that the cementum extracts can be used as the implantal coating materials in order to achieve an ideal osteointegration.
13 Bonding Strength of the Ag/Cu Bimetallic Strips Prepared by Roll Bonding at Different Temperatures
2003(7):530-533.
Abstract:
通过轧制复合方法，在不同温度条件下制备了Ag／Cu双金属板，研究了剥离载荷作用下分离强度与复合温度的关系，测定了复合基体的硬度并观察了分离界面形貌。结果表明：350℃复合的试样因具有较大面积的异种金属冶金结合区域而导致其分离强度较高；低于350℃复合试样的冶金结合区域减少，高于350℃复合试样的金属表面趋向于被连续分布的氧化物隔离，这两种情况均会使分离强度下降。
通过轧制复合方法，在不同温度条件下制备了Ag／Cu双金属板，研究了剥离载荷作用下分离强度与复合温度的关系，测定了复合基体的硬度并观察了分离界面形貌。结果表明：350℃复合的试样因具有较大面积的异种金属冶金结合区域而导致其分离强度较高；低于350℃复合试样的冶金结合区域减少，高于350℃复合试样的金属表面趋向于被连续分布的氧化物隔离，这两种情况均会使分离强度下降。
2003(7):534-537.
Abstract:
The effects of mullite coating by sol-gel method and the particle sizes of SiC on the oxidation behavior of the recrystallized SiC were studied. The results showed that the oxidation resistance could be increased by the mullite coating formed on the surface of recrystallized silicon carbide at high temperature and with the increase of the thickness of mullite coating, having well effects both by mullite coating and coarse particles of the recrystallized SiC.
The effects of mullite coating by sol-gel method and the particle sizes of SiC on the oxidation behavior of the recrystallized SiC were studied. The results showed that the oxidation resistance could be increased by the mullite coating formed on the surface of recrystallized silicon carbide at high temperature and with the increase of the thickness of mullite coating, having well effects both by mullite coating and coarse particles of the recrystallized SiC.
2003(7):538-541.
Abstract:
主要研究了形变和相变交互作用对等温锻件显微组织和力学性能的影响规律。结果发现形变和相变交互作用对Ti-17合金等温锻件的显微组织、力学性能有重大影响，经1次在β相区等温形变与相变交互作用，锻件高倍组织中的α相呈鱼骨状，在两相区等温锻造后，得到有较厚α片层的网篮状组织，各项力学性能指标均较差；经β相区和α β两相区2次以上形变和相变交互作用并在β相区等温锻造后，得到的网篮组织中的条状α细小均匀，交互作用次数愈多，α条愈细小、扭曲；如果交互作用次数少，在两相区等温锻造后只能得到具有较厚α片层的网篮组织，交互作用次数多，则得到的是细小均匀的球状α组织，但各项力学性能指标均满足要求。
主要研究了形变和相变交互作用对等温锻件显微组织和力学性能的影响规律。结果发现形变和相变交互作用对Ti-17合金等温锻件的显微组织、力学性能有重大影响，经1次在β相区等温形变与相变交互作用，锻件高倍组织中的α相呈鱼骨状，在两相区等温锻造后，得到有较厚α片层的网篮状组织，各项力学性能指标均较差；经β相区和α β两相区2次以上形变和相变交互作用并在β相区等温锻造后，得到的网篮组织中的条状α细小均匀，交互作用次数愈多，α条愈细小、扭曲；如果交互作用次数少，在两相区等温锻造后只能得到具有较厚α片层的网篮组织，交互作用次数多，则得到的是细小均匀的球状α组织，但各项力学性能指标均满足要求。
2003(7):542-545.
Abstract:
采用Ag粉和Ti粉作为焊料，对再结晶SiC陶瓷进行热压反应连接。研究了2种工艺，其中工艺1与传统的扩散焊工艺相似，即分别在不同的焊接温度下保温一定的时间；而工艺2则是首先在某一较高温度下进行短时间的保温，以利于Ti与SiC母材发生适度的界面反应，促进界面结合，同时液相银的出现将显著缓解焊接应力，随后在另一相对较低的温度下保温较长时间，以利于Ag—Ti金属间化合物的形成，有利于提高接头的焊接强度和工作温度。结果表明，采用工艺2获得的接头抗弯强度较高，达到SiC陶瓷母材强度的73．4％。微观结构研究表明，在界面处生成了反应层，焊料产物主要由两种相相间组成。EDX分析结果表明，界面处发生了元素的互扩散。
采用Ag粉和Ti粉作为焊料，对再结晶SiC陶瓷进行热压反应连接。研究了2种工艺，其中工艺1与传统的扩散焊工艺相似，即分别在不同的焊接温度下保温一定的时间；而工艺2则是首先在某一较高温度下进行短时间的保温，以利于Ti与SiC母材发生适度的界面反应，促进界面结合，同时液相银的出现将显著缓解焊接应力，随后在另一相对较低的温度下保温较长时间，以利于Ag—Ti金属间化合物的形成，有利于提高接头的焊接强度和工作温度。结果表明，采用工艺2获得的接头抗弯强度较高，达到SiC陶瓷母材强度的73．4％。微观结构研究表明，在界面处生成了反应层，焊料产物主要由两种相相间组成。EDX分析结果表明，界面处发生了元素的互扩散。
2003(7):546-549.
Abstract:
采用溶胶-凝胶法制备了微量 Yb2O3掺杂纳米 TiO2颗粒,采用 XRD, TG-DTA, TEM等手段对试样经不同温度热处理后的结构相变、表面形貌、颗粒大小等特性进行了表征.实验表明温度不高于 400℃时,试样的颗粒粒径较小,粒径在 15 nm以下,比表面积大于 107.22 m2@ g-1, TiO2呈锐钛型;在 400℃以上, TiO2粒径迅速增大,微粒出现锐钛相与金红石相混晶结构;800℃时 TiO2微粒完全转化成金红石相.
采用溶胶-凝胶法制备了微量 Yb2O3掺杂纳米 TiO2颗粒,采用 XRD, TG-DTA, TEM等手段对试样经不同温度热处理后的结构相变、表面形貌、颗粒大小等特性进行了表征.实验表明温度不高于 400℃时,试样的颗粒粒径较小,粒径在 15 nm以下,比表面积大于 107.22 m2@ g-1, TiO2呈锐钛型;在 400℃以上, TiO2粒径迅速增大,微粒出现锐钛相与金红石相混晶结构;800℃时 TiO2微粒完全转化成金红石相.
2003(7):550-553.
Abstract:
为系统地阐述送粉激光熔覆过程中激光能量的分配关系，在分析熔覆材料和基体材料与激光相互作用的基础上，提出了激光能量有效利用率的概念，给出了检测方法，并系统分析了影响因素。结果表明：在相同的送粉速率下，随扫描速度的增加，熔覆材料吸收的能量增加，基体材料吸收的能量减少，激光能量有效利用率增大；在相同的扫描速度下，随送粉速率的增加，熔覆材料吸收的能量增加，基体材料吸收的能量减少，激光能量有效利用率增大。对激光能量有效利用率随扫描速度变化出现最大值的现象给出了合理的解释。为定量描述激光熔覆工艺与工艺结果之间的关系奠定了基础。
为系统地阐述送粉激光熔覆过程中激光能量的分配关系，在分析熔覆材料和基体材料与激光相互作用的基础上，提出了激光能量有效利用率的概念，给出了检测方法，并系统分析了影响因素。结果表明：在相同的送粉速率下，随扫描速度的增加，熔覆材料吸收的能量增加，基体材料吸收的能量减少，激光能量有效利用率增大；在相同的扫描速度下，随送粉速率的增加，熔覆材料吸收的能量增加，基体材料吸收的能量减少，激光能量有效利用率增大。对激光能量有效利用率随扫描速度变化出现最大值的现象给出了合理的解释。为定量描述激光熔覆工艺与工艺结果之间的关系奠定了基础。
2003(7):554-557.
Abstract:
Ta/W/Sn multilayer coatings were made on LY12 aluminium substrate by plasma spray. Effect of various parameters on the melting degree and deposition efficiency of feedstock has been investigated.The surface and the interfaces morphology of the multilayer coatings were observed using scanning electron microscopy. The weight gain of the coatings was weighed using precision mechanical balance.The tensile strength of the multilayer was determinated by mechnical testing machine. The chemical composition of these coatings was seperately obtained using auger energy spectrum and chemical analysis.The result shows that Ta/W/Sn multilayer coatings with fine structure and uniform thickness could be prepared by plasma spray processes.The degree of the powders melting is much affected by spray power and spray rate,and does not vary much with spray distance within the specific range.
Ta/W/Sn multilayer coatings were made on LY12 aluminium substrate by plasma spray. Effect of various parameters on the melting degree and deposition efficiency of feedstock has been investigated.The surface and the interfaces morphology of the multilayer coatings were observed using scanning electron microscopy. The weight gain of the coatings was weighed using precision mechanical balance.The tensile strength of the multilayer was determinated by mechnical testing machine. The chemical composition of these coatings was seperately obtained using auger energy spectrum and chemical analysis.The result shows that Ta/W/Sn multilayer coatings with fine structure and uniform thickness could be prepared by plasma spray processes.The degree of the powders melting is much affected by spray power and spray rate,and does not vary much with spray distance within the specific range.
2003(7):561-565.
Abstract:
The effect of Ti/C (molar ratio) and Al content on phase constitution of combustion synthesized products by using Ti,Al,C and TiC powders as raw materials in the Ti Al C system has been studied. The experiment results show that the phase formation of combustion synthesized Ti3AlC2 powders are affected greatly by molar ratio of titanium to carbon and Al content in the raw materials. TiC is the main phase in the final product as the molar ratio of titanium to carbon is equal to 1 or 1.5, with little relationship to the amount of aluminum content. The Ti3AlC2 and Ti2AlC are the main phases in the final product as the molar ratio of titanium to carbon are equal to 2 and 3, respectively. Moreover, amounts of Ti3AlC2 and Ti2AlC increase in direct ratio with Al content, and later decrease with continuously increasing amount of Al. TiC is a medium product during the combustion process for the purpose of obtaining Ti3AlC2 powders.
The effect of Ti/C (molar ratio) and Al content on phase constitution of combustion synthesized products by using Ti,Al,C and TiC powders as raw materials in the Ti Al C system has been studied. The experiment results show that the phase formation of combustion synthesized Ti3AlC2 powders are affected greatly by molar ratio of titanium to carbon and Al content in the raw materials. TiC is the main phase in the final product as the molar ratio of titanium to carbon is equal to 1 or 1.5, with little relationship to the amount of aluminum content. The Ti3AlC2 and Ti2AlC are the main phases in the final product as the molar ratio of titanium to carbon are equal to 2 and 3, respectively. Moreover, amounts of Ti3AlC2 and Ti2AlC increase in direct ratio with Al content, and later decrease with continuously increasing amount of Al. TiC is a medium product during the combustion process for the purpose of obtaining Ti3AlC2 powders.
2003(7):566-568.
Abstract:
在(α+β)两相区对Ti-1023合金进行等温压缩试验,实测高温流动应力曲线,讨论流动应力及显微组织随温度及应变速率的变化规律,实验结果表明,Ti-1023合金的流动应力对应变速率非常敏感;变形温度对流动应力的影响程度与应变速率大小有关,在ε=1.0s-1的较快速变形时,当温度由760℃提高到800℃时,流动应力值下降约40MPa,而在ε=1.6×10-4s-1的慢速变形时,流动应力值仅下降10MPa;显微组织观察结果表明,在相同温度下较快速变形时(ε=1.0s-1),所得显微组织比较细小、均匀,而慢速变形时(ε=1.6×10-4s-1),初生α相及组织比较粗大,亚β晶界也比较明显。因此,在保证锻件良好成形的前提下,Ti-1023合金在等温锻造时可采用适当大的应变速率。
在(α+β)两相区对Ti-1023合金进行等温压缩试验,实测高温流动应力曲线,讨论流动应力及显微组织随温度及应变速率的变化规律,实验结果表明,Ti-1023合金的流动应力对应变速率非常敏感;变形温度对流动应力的影响程度与应变速率大小有关,在ε=1.0s-1的较快速变形时,当温度由760℃提高到800℃时,流动应力值下降约40MPa,而在ε=1.6×10-4s-1的慢速变形时,流动应力值仅下降10MPa;显微组织观察结果表明,在相同温度下较快速变形时(ε=1.0s-1),所得显微组织比较细小、均匀,而慢速变形时(ε=1.6×10-4s-1),初生α相及组织比较粗大,亚β晶界也比较明显。因此,在保证锻件良好成形的前提下,Ti-1023合金在等温锻造时可采用适当大的应变速率。
22 Microstructure of Laser Clad TiC/FeAl Composite Coating and Growth Mechanism of Primary TiC Carbide
2003(7):569-572.
Abstract:
A rapidly solidified TiC/FeAl composite coating was fabricated on substrate of 1Cr18Ni9Ti stainless steel by laser cladding. The microstructure of composite coating, the growth morphology and growth mechanism of primary TiC carbide were investigated. Results show that the laser clad coating has a microstructure consisting of primary TiC,primary dendritic FeAl and small amount of interdendritic FeAl/TiC eutectic. The primary TiC carbide has an unique growth morphology of radial branching faceted dendritic colony, and its growth mechanism is still lateral growth.
A rapidly solidified TiC/FeAl composite coating was fabricated on substrate of 1Cr18Ni9Ti stainless steel by laser cladding. The microstructure of composite coating, the growth morphology and growth mechanism of primary TiC carbide were investigated. Results show that the laser clad coating has a microstructure consisting of primary TiC,primary dendritic FeAl and small amount of interdendritic FeAl/TiC eutectic. The primary TiC carbide has an unique growth morphology of radial branching faceted dendritic colony, and its growth mechanism is still lateral growth.
2003(7):573-576.
Abstract:
Worm powder extrusion molding(PEM) technology of hardmetal powder using novel binder system has been probed into. A newly developed binder system comprises a major fraction of low molecular weight components(LMWC) and a minor fraction of polymer.The binder was fabricated by heating melting method combined with solvent solving. The feedstock was mixed as a thick slurry at room temperature and was rapidly homogenised by stirring at a adequate shear force. The microstructure of the moulded specimes was observed by scanning electronics microscopy(SEM). The binder was debinded step by step. At the first stage of debinding, the LMWC were removed, and the interconnected capillaries were formed in the moluded green bodies. At the second stage of debinding, the remaining high molecular weight components were completely removed out. The second stage debinding heating rate can be faster than the first stage. The thermal debinding mechanism was studied by thermogravimetry (TG) and differential thermogravimetry(DTG). This research shows that the thermal debinding rate is controlled by three dimensional diffusion mechanism. The PEM hardmetal products with good properties and diameters of up to 20mm have been manufactured.
Worm powder extrusion molding(PEM) technology of hardmetal powder using novel binder system has been probed into. A newly developed binder system comprises a major fraction of low molecular weight components(LMWC) and a minor fraction of polymer.The binder was fabricated by heating melting method combined with solvent solving. The feedstock was mixed as a thick slurry at room temperature and was rapidly homogenised by stirring at a adequate shear force. The microstructure of the moulded specimes was observed by scanning electronics microscopy(SEM). The binder was debinded step by step. At the first stage of debinding, the LMWC were removed, and the interconnected capillaries were formed in the moluded green bodies. At the second stage of debinding, the remaining high molecular weight components were completely removed out. The second stage debinding heating rate can be faster than the first stage. The thermal debinding mechanism was studied by thermogravimetry (TG) and differential thermogravimetry(DTG). This research shows that the thermal debinding rate is controlled by three dimensional diffusion mechanism. The PEM hardmetal products with good properties and diameters of up to 20mm have been manufactured.
