Deformation behavior of HCP Ti-Al alloy single crystals

Single crystals of Ti-Al alloys containing 1.4, 2.9, 5, and 6.6 pct Al (by weight) were oriented for 〈a〉 slip on either basal or prism planes or loaded parallel along the c-axis to enforce a nonbasal deformation mode. Most of the tests were conducted in compression and at temperatures between 77 and 1000 K. Trace analysis of prepolished surfaces enabled identification of the twin or slip systems primarily responsible for deformation. Increasing the deformation temperature, Al content, or both, acted to inhibit secondary twin and slip systems, thereby increasing the tendency toward strain accommodation by a single slip system having the highest resolved stress. In the crystals oriented for basal slip, transitions from twinning to multiple slip and, finally, to basal slip occurred with increasing temperature in the lower-Al-content alloys, whereas for Ti-6.6 pct Al, only basal slip was observed at all temperatures tested. A comparison of the critically resolved shear stress (CRSS) values for basal and prism slip as a function of Al content shows that prism slip is favored at room temperature in pure Ti, but the stress to activate these two systems becomes essentially equal in the Ti-6.6 pct Al crystals over a wide range of temperatures. Compression tests on crystals oriented so that the load was applied parallel to the c-axis showed extensive twinning in lower Al concentrations and 〈c+a〉 slip at higher Al concentrations, with a mixture of 〈c+a〉 slip and twinning at intermediate compositions. A few tests also were conducted in tension, with the load applied parallel to the c-axis. In these cases, twinning was observed, and the resolved shear for plastic deformation by twinning was much lower that that for 〈c+a〉 slip observed in compression loading. This article is based on a presentation made in the symposium entitled “Defect Properties and Mechanical Behavior of HCP Metals and Alloys” at the TMS Annual Meeting, February 11–15, 2001, in New Orleans, Louisiana, under the auspices of the following ASM committees: Materials Science and Critical Technology Sector, Structural Materials Division, Electronic, Magnetic & Photonic Materials Division, Chemistry & Physics of Materials Committee, Joint Nuclear Materials Committee, and Titanium Committee.     

Hydrogen-assisted stress cracking of high-strength wheel bolts

Early failures occurred with two sizes of wheel bolts used for attaching front wheels and dual rear wheels to heavy truck hubs. Failure resulted in fracture of the bolts, and was a response to the material and process specification which produced a steel microstructure highly susceptible to hydrogen-assisted stress cracking. The microstructure resulted from an alloy steel that was carburized, heat treated, and then zinc plated. This combination of material and processing produced a high-strength SAE Grade 8 bolt (equivalent to an ISO 10.9 grade) with a hard, brittle case and an anodic zinc coating. A slight misalignment of the wheel bolt coupled with a ball seat mounting design for the wheel nuts created a combined axial and bending stress that exceeded the threshold for hydrogen-assisted stress cracking.     

Filial therapy with immigrant Chinese families.

The purpose of this study was to determine the effectiveness of filial therapy as a method of prevention and intervention for immigrant Chinese families in Canada. Results of the analyses of covariance indicate that parents in the experimental group demonstrated a significant increase in empathic interaction with their children, a significant increase in acceptance of their children, a significant reduction of perceived stress related to parenting, and a significant reduction of perceived problems related to their children's behavior. Children of parents in the experimental group demonstrated a significant increase in self-concept. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effectiveness of child-centered play therapy on developmental and diagnostic factors in children who are homeless.

Children who are homeless have numerous emotional, social, behavioral, and developmental challenges. This pilot research study examined the effectiveness of child-centered play therapy on developmental and diagnostic factors in 36 elementary schoolchildren who are homeless. Results indicate statistically significant improvement in 1 of 2 developmental strands and 1 of 3 diagnostic profiles as measured by the Boxall Profile. Specifically, children who are homeless improved in internalization of controls and self-limiting features and showed positive trends in unsupported development. Effect sizes ranged from small to medium. The findings are congruent with previous research that indicates that child-centered play therapy may have a positive impact on children who are homeless and on children's development within the classroom. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Child-Centered Play Therapy with Children who are Homeless: Perspective and Procedures.

Children who are homeless are one of the fastest growing populations. However, the literature on play therapy with children who are homeless is sparse. This article provides play therapists with needed perspective of prevalence, causes, and mental health impact of homelessness. A Child-Centered Play Therapy approach, which emphasizes a safe relationship based on the core conditions, is recommended. Procedures to meet the needs of children who are homeless and to enlarge the meaning of their unique play themes, such as eviction and "I'm rich," are discussed. Play therapists are encouraged to fulfill their social responsibility by providing play therapy for children who are homeless. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Effects of Child-Centered Group Play Therapy on Self-Concept, Depression, and Anxiety of Children Who Are Homeless.

Children who are homeless are a growing population. They face numerous challenges including decreased self-esteem and increased depression and anxiety. The purpose of this research study was to determine if child-centered group play therapy significantly increased self-esteem and significantly decreased depression and anxiety of 42 children who were homeless. Statistical analysis revealed children receiving child-centered play therapy significantly improved in self-esteem, anxiety, and depression demonstrating a moderate to large effect size. A discussion of these results, research limitations, and future research directions are provided. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Building a firm foundation in play therapy research: Response to Phillips (2010).

This article is a response to Phillips’s (see record 2010-01037-002) article titled “How Firm Is Our Foundation? Current Play Therapy Research.” Strengths of Phillips’s article are identified as (a) recognition of evidence-based standards in scientific literature, (b) challenge for methodologically sound studies, and (c) clear recommendations for future research. Responses to his concerns were addressed by (a) identifying credible scientific evidence of recent play therapy research studies, (b) providing a balanced interpretation of Bratton, Ray, Rhine, and Jones’s (2005) meta-analysis, and (c) replying to metaquestions in play therapy research. The authors conclude that play therapy researchers have made steady progress in building a firm foundation of play therapy research and continue to do so. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Learning more about those who play in session: The National Play Therapy in Counseling Practices Project (Phase I).

Through a joint research committee sponsored by the Association for Play Therapy (APT) and the American Counseling Association (ACA), The National Play Therapy in Counseling Practices Project conducted the first phase of investigation. Findings offered a snapshot of mental health providers of play therapy, regarding the nature of who they are and what they do. In terms of training, play modalities, theoretical orientation, and employment setting, comparisons were made based on membership of participants in ACA or APT. Further research was suggested to examine the effectiveness of play therapy with specific therapeutic issues. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Preparing play therapists for disaster response: Principles and procedures.

In the wake of numerous recent natural disasters such as the 2004 tsunami and 2005 hurricanes, play therapists have been asked to provide disaster response. However, the role of disaster response interventionists is vastly different from the typical role of play therapists. In order for play therapists to be prepared for disaster response, an explanation of disaster response principles and procedures is needed. This article will help educate play therapists about how to use their play therapy skills and knowledge in a disaster response environment. Specifically, this article will (a) explain basic principles such as following the Incident Command Structure; (b) discuss the play therapist's role in disaster response in light of the phase of disaster; and (c) recommend disaster response procedures. Examples from APT members' response to the tsunami and Hurricane Katrina are provided. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Deformation behavior of HCP Ti-Al alloy single crystals

Single crystals of Ti-Al alloys containing 1.4, 2.9, 5, and 6.6 pct Al (by weight) were oriented for <a> slip on either basal or prism planes or loaded parallel along the c-axis to enforce a nonbasal deformation mode. Most of the tests were conducted in compression and temperatures between 77 and 1000 K. Trace analysis of prepolished surfaces enabled identification of the twin or slip systems primarily responsible for deformation. Increasing the deformation temperature, Al content, or both, acted to inhibit secondary twin and slip systems, thereby increasing the tendency toward strain accommodation by a single slip system having the highest resolved stress. In the crystals oriented for basal slip transitions from twinning to multiple slip and, finally, to basal slip occurred with increasing temprature in the lower-Al-content alloys, whereas for Ti-6.6 pct Al, only basal slip was observed at all temperatures tested. A comparison of the critically resolved shear stress (CRSS) values for basal and prism slip as a function of Al content shows that prism slip is favored at room temperature in pure Ti, but the stress to activate these two systems becomes essentially equal in the Ti-6.6 pct Al crystals over a wide range of temperatures. Compression tests on crystals oriented so that the load was applied parallel to the c-axis showed extensive twinning in lower Al concentrations and <c+a> slip at higher Al concentrations, with a mixture of <c+a> slip and twinning at intermediate compositions. A few tests also were conducted in tension, with the load applied parallel to the c-axis. In these cases, twinning was observed, and the resolved shear for plastic deformation by twinning was much lower that that, for <c+a> slip observed in compression loading. This article is based on a presentation made in the symposium entitled “Defect Properties and Mechanical Behavior of HCP Metals and Alloys” at the TMS Annual Meeting, February 11–15, 2001, in New Orleans, Louisiana, under the auspices of the following ASM committees: Materials Science and Critical Technology Sector, Structural Materials Division, Electronic, Magnetic & Photonic Materials Division, Chemistry & Physics of Materials Committee, Joint Nuclear Materials Committee, and Titanium Committee.