The CoCuFeNiTi high entropy alloy coating was prepared by laser cladding technology on the surface of 40 Cr steel, which then was characterized by means of SEM, XRD and EDS, as well as microhardness tester, wear resistance and corrosion resistance test. The results show that among others the coating prepared by laser beam with power of 700 W and scanning speed of 6 mm/s presents the best in surface quality and metallurgical bonding between the coating and the substrate. The coating is mainly composed of FCC phase, a small amount of Cu₄Ti phase and nano precipitates rich in Cu. The microstructure of the coating shows typical dendrite structure, while Cu segregated in between dendrites as micro- and/or nano-particulates rich in Cu. The microhardness of the coating is 438.83HV, which is 1.7 times that of 40 Cr steel. The wear mass loss of the coating is about 1/2 that of 40 Cr steel, indicating the coating has better wear resistance. The wear of the coating is mainly adhesive wear, accompanied by a certain degree of abrasive grain wear. The corrosion resistance of the coating in acidic medium of pH=4 and 3.5%NaCl solution was better than that of 40 Cr steel.

The Fe-Al coating, with compactness, stiffness, and continuity, could be prepared on Q235 low carbon steel by pack aluminizing. The phase structure, morphology, composition, and hardness of the prepared coating were characterized by XRD, SEM, EDS, and micro-hardness tester respectively. Results indicate that the Fe-Al coating is composed of Fe₂Al₅ and FeAl₃ phases, whilst, the coating fabricated at 750℃ is particularly rich in Fe₂Al₅ phase. With the rising temperature, the thickness of Fe-Al coating increases, whereas the micro-hardness decreases. As a result of aluminizing for different time, the formed coatings are composed of the two phases Fe₂Al₅ and FeAl₃ as well. However, with the increasing aluminizing time, the content of FeAl₃ phase decreases, while the micro-hardness of the coating decreases slightly. Finally, a diffusion mechanism related with the formation of Fe-Al coating is proposed based on the comprehensive analysis on the thermodynamics and kinetics of pack aluminizing process.

The stress-strain curves of Ti-6Al-4V alloy during hot deformation by applied strain rate within the range of 5×10^-4~5×10^-2 s^-1 at 870~960°C were measured via single-pass isothermal compression test. The dynamics characteristics of rheological stress, critical strain capacity and structure evolution of the alloy during dynamic recrystallization were systematically illustrated by means of KM model, Poliak-Jonas model, and Avrami model. Then a concept of volume fraction of the microstructure transformation, i.e., the portion of the alloy that has been underwent microstructure transformation during dynamic recrystallization, was introduced into the so called prasad power dissipation rate model, thus the energy variation of the alloy during dynamic recrystallization was acquired. Further, taking both of the acquired energy variation and the observed microstructure evolution characteristics together into consideration, the dynamic recrystallization mechanism of Ti-6Al-4V alloy may be revealed. It follows that the critical strain capacity of Ti-6Al-4V during dynamic recrystallization decreased and the structural transformation volume fraction increased following the rise of deformation temperature or the decline of strain rate. The power dissipation rate upon complete dynamic recrystallization is larger than 0.34, and the forming mechanism is a dislocation-induced arcuation nucleation mechanism.

The quaternary-system Lu/In/Tm/Yb carbonat-recursors were synthesized by chemical precipitation route, and then were calcinated at 1100℃ to acquire a series of sphere-like [(Lu_0.5In_0.5)_0.999-x-Tm_0.001Yb_x]₂O₃ (x=0~0.05) solid solution-oxides with average particle size of about 110 nm. Under 980 nm laser excitation the oxide powder exhibits strong bluish emission at about 450∼510 nm and weak red emission at about 650~670 nm arising from ¹D₂→³H₆,³F₄ and ¹G₄→³F₄ transitions of Tm³⁺, respectively. Their upconversion mechanisms may be ascribed to the above two-phonon processes. The color of the emitted light on the 1931CIE color coordinates gradually move from green (0.31, 0.54) to blue (0.01, 0.19) colors with the increasing Yb³⁺ concentration. Yb³⁺ co-doping effectively enhances the luminescence intensity of Tm³⁺ and its optimum content is 2.5%. The fluorescence lifetimes of the oxide powder were measured to be about 0.84 for the 474 nm blue emission and 0.97 ms for the 654 nm red emission.

Foamed stainless steels 410L and 430L with different porosity were made respectively with powders of the two steels as raw material and CaCl₂ as pore-forming agent via a two-step process i.e., powder metallurgy sintering and post dissolution. Then their microstructure and properties were comparatively assessed. The results show that the two foamed steels of 410L and 430L are composed of merely α-Fe phase. More serious oxidation can be observed on the walls of the as fresh made 410 steel foams rather than that of 430 SS steel foams. The 430L stainless steel foam presents higher corrosion resistance than the 410L stainless steel foam. The compression test results reveal that the yield stress of 410L steel foams with porosity of 73%~83% is in the range of 22.06~5.45 MPa, the yield stress of 430L steel foams with porosity of 72%~83% is in the range of 56.77~10.44 MPa, hence, the compressive strength of 430L steel foam is 2~3 times that of 410L steel foam. Besides, when the strain reaches 50%, 410L steel foams with porosity of 73%~83% have 6.12~2.90 MJ/m³ energy absorption value per unit volume, while the corresponding value for 430L steel foams with porosity of 72%~83% is 40.35~8.25 MJ/m³. Therefore, the energy absorption value per unit volume of 430L steel foams is about 3~5 times that of 410L steel foams.

The laser selectively melted 17-4PH stainless steel was subjected to different post-heat treatment, i.e. vacuum heat treatment (1040℃/2 h+water quenching and 480℃/4 h+water quenching), hot isostatic pressing heat treatment (1040℃-150 MPa/2 h HIP +gas rapid cooling and vacuum 480℃-100 MPa/4 h+GRC) and combined heat treatment (1040℃-150 MPa/2 h HIP+GRC and vacuum 480℃/4 h+water quenching). Afterwards, the microstructure and mechanical performance of the laser melted steels were characterized by means of optical microscopy, electron scanning microscopy, microhardness tester and universal tensile tester. The results show that the vacuum heat treatment can reduce the inner pore size down to 3~7 μm. After hot isostatic pressing treatment, all pores almost closed and the density is almost of the theoretical value of the laser deposited 17-4PH stainless stee. After heat treatment, the 17-4PH stainless steel composed of tempered- and quenched-martensite, and the precipitates with size of 100~150 nm dispersed in grains. Vacuum heat treatment + water quenching can significantly increase the tensile strength and hardness of the deposited 17-4PH stainless steel to 1300 MPa and 448.5HV, respectively. Hot isostatic pressing heat treatment can significantly increase the tensile strength of the deposited 17-4PH stainless steel, at the same time, its elongation at break reaches 22.4%.The fracture morphology of the as deposited 17-4PH SS and the one after hot isostatic pressing heat treatment was typical ductile fracture, and the dimples of hot isostatic pressing heat treatment ones were larger in size and deeper in depth. The fracture morphologies of the deposited 17-4PH SS after vacuum heat treatment and combined heat treatment have the characteristics of partial brittle fracture and emergence of a few cracks, whilst who's plasticity decreases slightly, in comparison with that of the as deposited ones.

The effect of P addition on the microstructure, oxidation resistance, wettability and corrosion resistance of Sn-9Zn-0.1S solder alloy were characterized via optical microscope observation, scanning electron microscopy (SEM) and X-ray diffractometer (XRD), as well as dross removal measurement at different temperatures, spreading area on Cu plate and weight loss measurement after immersion in HCl solution respectively. The results show that P addition can refine the lamellar eutectic microstructures, but coarsen the rod-like primary Zn-rich phases. The oxidation resistance and wettability of the solder can be firstly increased with the addition of P, then this effect reduces, and the optimal P content is 0.06% (mass fraction). At the same time, a suitable amount of P addition can also improve the corrosion resistance of Sn-9Zn-0.1S solder alloy by modifying its microstructure and increasing the density of corrosion products. It is found that the weight loss is the minimum when the P content is 0.1% (mass fraction).

Based on the TC4 Ti-alloy core formed by alternating pin-press method at high-temperature, the laser welding connection process of the panel and the core was investigated in order to manufacture the pyramid lattice structure of Ti-alloy. The laser welding parameters were optimized by response surface method, the plane and core of lattice structure were connected, the microstructures of welding joints were examined, and the compression performance of lattice structure was investigated. The results show that the laser power has the most significant influence on the welding result. The optimized parameters of laser welding of lattice structure face core were as follows: welding power of upper panel was 1.4 kW, welding power of lower panel was 1.2 kW, defocusing quantity was 30mm, and residence time was 1 s. The martensite transformation of Ti-alloy occurred, and a large number of acicular martensite phases distributed in the heat affected zone of laser welding. The microstructure of welding zone was coarse β phase and acicular α phase. The microhardness decreased from the weld zone to the base metal in the welding joints with the decreasing of martensite phase. Based on the compression process recorded by the camera the deformation and failure process of the pyramid lattice structure were analyzed. The failure fracture of truss rod occurred in the heat-affected zone. The compression pressure strength and modulus of the TC4 Ti-alloy lattice structure manufactured by laser welding were 3.09 MPa and 153.25 MPa, respectively.

A rapid degradation material, ferric chloride (FeCl₃) catalyzed polylactic acid (PLA) PLA/FeCl₃ was prepared by the melt blending method, which presents degradation rate of 10 times higher than that of bare PLA. However, the molecular weight of PLA/FeCl₃ is greatly reduced during the processing, which results in decrease in mechanical properties and processability. In order to reduce the over-degradation of PLA/FeCl₃ in melt processing, triphenyl phosphite (TPPi), which has excellent chain extension and plasticizing effect, was introduced into the PLA/FeCl₃ system and melt blended to improve its comprehensive mechanical properties. The degradation rate and comprehensive performance of the prepared samples were investigated via alkaline solution degradation test and various test methods. The results show that the sample P3-1 had the best performance when the ratio of TPPi to FeCl₃ was 3∶1, namely, the tensile strength and flexural strength reached 43.78 MPa and 99.04 MPa, respectively. The mass loss rate of degradation for 8d in alkaline solution is 65.76%, which was much higher than that of 4.67% for bare PLA. The sample containing 2.95 phr FeCl₃ has been able to produce a high degradation rate in the alkaline solution without over-degradation during the processing, thereby obtaining a modified PLA material that can quickly degrade and maintain good mechanical properties.